1) 26.2 m/s
The mechanical energy of the divers at any point of their vertical motion is sum of the kinetic energy and the gravitational potential energy:
[tex]E=K+U = \frac{1}{2}mv^2 + mgh[/tex]
where
m is the mass of the diver
v is the speed
g = 9.8 m/s^2 is the acceleration due to gravity
h is the height above the water
When the diver is on the cliff, v = 0 (he is at rest), so K=0 and the initial mechanical energy is just potential energy:
[tex]E_i = mgh[/tex]
where h=35 m is the height of the cliff.
When the diver hits the water above, h = 0, so U=0 and the final mechanical energy is just kinetic energy:
[tex]E_f = \frac{1}{2}mv^2[/tex]
since the total mechanical energy is conserved, we have
[tex]E_i = E_f\\mgh = \frac{1}{2}mv^2[/tex]
And solving the equation for v, we find the speed when they reach the surface of the water:
[tex]v=\sqrt{2gh}=\sqrt{2(9.8 m/s^2)(35 m)}=26.2 m/s[/tex]
2) It is converted into thermal energy of the water
When the diver enters the water, he suddenly feels another force acting against the motion of the diver: the resistance of the water. The resistance of the water acts upward, slowing down the diver until he stops.
In this process, the speed of the diver (v) decreases, and therefore the kinetic energy of the diver decreases as well, until it becomes zero.
However, this does not mean that the conservation of energy has been violated. In fact, the kinetic energy of the diver has been converted into thermal energy of the molecules of water surrounding the diver.
Which of the following technologies would produce the most energy in light waves?
A.Halogen lightbulb
B.Radio-controlled toy airplane
C.Microwave industrial drying equipment
D.Ultraviolet disinfecting wand
Answer:
D. Ultraviolet disinfecting wand.
Explanation:
Energy in light waves depends upon the frequency o the waves. Higher the frequency of the waves, higher the amount of energy it carries. Similarly, waves with shorter wavelength has higher frequencies and thus more energy.
Ultraviolet disinfecting wand would produce most energy out of the four options because it produce UV waves which have shorter wavelength and higher frequency.
Answer: (B): Radio-controlled airplane
Explanation:
A P E X
1.Work is only being done when what happens to an object?
A) the object does not move
B) the object disappears without explanation
C) it moves in the same direction as the force
D) The object moves in the opposite direction of the force
2.Ben and Jerry, arch rivals, decide to have a weight lifting contest during PE. Ready, set, go! Ben and Jerry both lift a 250 kg barbell 10 times over their heads. They are approximately the same height and lift the barbell the same distance in the air. It takes Ben 5 seconds to complete 10 lifts; it takes Jerry 25 seconds to complete his 10 lifts.
Which statement is MOST accurate regarding the weightlifting contest?
A) Ben did more work than Jerry.
B) Ben has more power than Jerry.
C) Ben and Jerry have the same power.
D) Ben does more work and is more powerful than Jerry.
3.Which energy source can be found on the electromagnetic spectrum?
A) sound energy
B) chemical energy
C) UV light energy
D) mechanical energy
4. Sam blew up a balloon and rubbed it on his head. Then he stuck the balloon on the wall. This was all the result of electrostatics or the transfer of charge. The appearance of negative charge on a balloon is the result of its gaining electrons. And these electrons must come from somewhere; in this case, from Sam's hair. Electrons are transferred in any charging process. In the case of charging by friction, they are transferred between the two objects being rubbed together. Prior to the charging, both objects are electrically neutral and the situation obeys the law of conservation of charge. How does the law of conservation of charge explain Sam and his balloon?
A) Friction creates charge that collected on the balloon.
B) The balloon gained electrons; Sam's hair gained protons.
C) If the balloon acquires charge, Sam's hair loses charge.
D) The net charge before is zero; the net charge after is negative.
1.
C) it moves in the same direction as the force
D) The object moves in the opposite direction of the force
Work is defined as follows:
[tex]W=Fdcos \theta[/tex]
where
F is the magnitude of the force applied on an object
d is the displacement of the object
[tex]\theta[/tex] is the angle between the direction of the force and of the displacement
As we see from the formula, when d=0 (the object does not move), then W=0 (no work done). While we have work done if the object is moving. In particular, we have two situations:
- The object moves in the same direction as the force: [tex]\theta=0^{\circ}[/tex], so [tex]cos \theta= 1[/tex] and the work done is positive
- The object moves in the opposite direction of the force: [tex]\theta=180^{\circ}[/tex], so [tex]cos \theta= -1[/tex] and the work done is negative
2. B) Ben has more power than Jerry.
Power is defined as:
[tex]P=\frac{W}{t}[/tex] (1)
where
W is the work done
t is the time taken
Work is the product of force and displacement. Since Ben and Jerry lift the same mass (250 kg), they apply the same force, and since they lift the barbell the same distance in air the same number of times (10), the displacement is also the same: so, they did the same work.
However, Ben did it in less time (5 s) then Jerry (25 s): looking at eq.(1), we see that less time means more power, so Ben has more power than Jerry.
3. C) UV light energy
The electromagnetic spectrum is the classification of all electromagnetic waves according to their different wavelength.
From shortest to longest wavelength, we have:
Gamma rays
X-rays
UV (ultraviolet)
Visible light
Infrared radiation
Microwaves
Radio waves
So, we see that UV light energy (ultraviolet radiation) is a type of electromagnetic waves.
4. C) If the balloon acquires charge, Sam's hair loses charge
The law of conservation of charge applied to this case states that the total charge on Sam hair and the balloon before must be equal to the total charge after: no charge can be created or destroyed in the process, but only moved from one object to the other.
In this example, Sam rubs the balloon on his head: electrons are transferred from Sam's hair to the balloon's surface. Therefore, we can say that the balloon has acquired negative charge, while Sam's hair has lost negative charge.
If the path-length differences between two identical and coherent beams is two wavelengths when they arrive on a screen, will they produce a dark or a bright spot?
a. bright spotb. dark spot
Answer:
Bright spot
Explanation:
When we have interference between two identical and coherent beams, the conditions for constructive interference (bright spots) and destructive interference (dark spots) are:
- Costructive interference: the path-length differences between the two waves is an integer multiple of the wavelength of the waves:
[tex]|d_1 - d_2| = n \lambda[/tex]
where the term on the left is the path difference, and [tex]\lambda[/tex] is the wavelength
- Destructive interference: the path-length differences between the two waves is an odd multiple of half the wavelength of the waves:
[tex]|d_1 - d_2| = (n+\frac{1}{2}) \lambda[/tex]
In this problem, the path-length difference is 2 wavelengths: so, it is an integer multiple of the wavelength, therefore the point is a point of constructive inteference (bright spot).
A path-length difference of two wavelengths between two coherent beams results in a bright spot on the screen due to constructive interference. This is related to double slit experiments, which display evenly spaced bright fringes.
Explanation:If two identical and coherent beams of light have a path-length difference of two wavelengths when they arrive on a screen, they will produce a bright spot. This is because a path-length difference of an integer number of wavelengths, such as two wavelengths, results in constructive interference. Constructive interference occurs when the crest of one wave overlaps with the crest of another, leading to an increase in amplitude and thus a bright fringe on the screen. This principle is at work in both single and double slit experiments.
In the context of single slit and double slit interference, evenly spaced bright spots are a characteristic of double slit experiments. On the other hand, the observation that some bright spots are dimmer on either side of the center is typical in single slit interference patterns because of the different path lengths and resulting interference effects.
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The alpha particles leave visible tracks in the cloud chamber because
Ionization by the alpha particle seeds the formation of clouds where the particle has passed.
The kinetic energy of the alpha particles heats the air.
The alpha particle is so energetic that it leaves a smoke trail behind.
The alpha particle strikes nitrogen molecules and breaks them into atomic nitrogen.
The inner atmosphere of a cloud chamber is composed of an easily ionizable gas, this means that little energy is required to extract an electron from an atom. This gas is maintained in the supercooling state, so that a minimum disturbance is enough to condense it in the same way as the water is frozen.
Then, when a charged particle with enough energy interacts with this gas, it ionizes it.This is how alpha particles are able to ionize some atoms of the gas contained inside the chamber when they cross the cloud chamber.
These ionized atoms increase the surface tension of the gas around it allowing it to immediately congregate and condense, making it easily distinguishable inside the chamber like a small cloud. In this way, it is perfectly observable the path the individual particles have traveled, simply by observing the cloud traces left in the condensed gas.
Infrared rays have a shorter wavelength than
Answer:
Microwaves and radio waves
Explanation:
The electromagnetic spectrum is the classification of the electromagnetic waves according to their wavelength.
From shortest to longest wavelength, they are classified as follows:
Gamma rays < 6 pm
X-rays 6 pm - 10 nm
Ultraviolet 10 nm - 380 nm
Visible light 380 nm - 750 nm
Infrared radiation [tex]750 nm - 5 \mu m[/tex]
Microwaves [tex]5 \mu m -0.3 m[/tex]
Radio waves > 0.3 m
From the list, we see that infrared rays have shorter wavelength than microwaves and radiowaves.
Infrared rays have longer wavelengths than visible light and ultraviolet radiation, falling in the range of 0.74(5m) to 1 mm, and are typically emitted by objects near room temperature. They are lower in energy and frequency compared to ultraviolet radiation, and are responsible for the warming sensation experienced when absorbed by the skin.
In answer to your question: Infrared rays have a shorter wavelength than microwaves. Infrared radiation, including infrared rays, falls below visible light in the electromagnetic spectrum with longer wavelengths and shorter frequencies than visible light. It ranges from about 0.74 micrometers (5m) to 1 millimeter (mm), corresponding to frequencies roughly from 300 gigahertz (GHz) to 400 terahertz (THz). Infrared rays are of lower energy compared to not only visible light but also ultraviolet radiation, which has a shorter wavelength and higher frequency than both visible light and infrared radiation.
Objects near room temperature emit most of the thermal radiation in the infrared range. Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational movements. The sensation of warmth we often associate with infrared waves is due to the absorption of this radiation by our skin, which causes molecules to vibrate and increase in kinetic energy.
A small cork with an excess charge of +6.0µC is placed 0.12 m from another cork, which carries a charge of -4.3µC.
A) what is the magnitude of the eletric force between the corks?
B) is this force attractive or repulsive?
C) how many excess electrons are on the negative cork?
D) how many electrons has the postive cork lost?
A) 16.1 N
The magnitude of the electric force between the corks is given by Coulomb's law:
[tex]F=k\frac{q_1 q_2}{r^2}[/tex]
where
k is the Coulomb's constant
[tex]q_1 = 6.0 \mu C=6.0 \cdot 10^{-6} C[/tex] is the magnitude of the charge on the first cork
[tex]q_2 = 4.3 \mu C = 4.3 \cdot 10^{-6}C[/tex] is the magnitude of the charge of the second cork
r = 0.12 m is the separation between the two corks
Substituting numbers into the formula, we find
[tex]F=(9\cdot 10^9 N m^2 C^{-2} )\frac{(6.0\cdot 10^{-6}C)(4.3\cdot 10^{-6} C)}{(0.12 m)^2}=16.1 N[/tex]
B) Attractive
According to Coulomb's law, the direction of the electric force between two charged objects depends on the sign of the charge of the two objects.
In particular, we have:
- if the two objects have charges with same sign (e.g. positive-positive or negative-negative), the force is repulsive
- if the two objects have charges with opposite sign (e.g. positive-negative), the force is attractive
In this problem, we have
Cork 1 has a positive charge
Cork 2 has a negative charge
So, the force between them is attractive.
C) [tex]2.69\cdot 10^{13}[/tex]
The net charge of the negative cork is
[tex]q_2 = -4.3 \cdot 10^{-6}C[/tex]
We know that the charge of a single electron is
[tex]e=-1.6\cdot 10^{-19}C[/tex]
The net charge on the negative cork is due to the presence of N excess electrons, so we can write
[tex]q_2 = Ne[/tex]
and solving for N, we find the number of excess electrons:
[tex]N=\frac{q_2}{e}=\frac{-4.3\cdot 10^{-6} C}{-1.6\cdot 10^{-19} C}=2.69\cdot 10^{13}[/tex]
D) [tex]3.75\cdot 10^{13}[/tex]
The net charge on the positive cork is
[tex]q_1 = +6.0\cdot 10^{-6}C[/tex]
We know that the charge of a single electron is
[tex]e=-1.6\cdot 10^{-19}C[/tex]
The net charge on the positive cork is due to the "absence" of N excess electrons, so we can write
[tex]q_1 = -Ne[/tex]
and solving for N, we find the number of electrons lost by the cork:
[tex]N=-\frac{q_1}{e}=-\frac{+6.0\cdot 10^{-6} C}{-1.6\cdot 10^{-19} C}=3.75\cdot 10^{13}[/tex]
1) If a pendulum clock keeps perfect time at the base of a mountain, will it also keep perfect time when it is moved to the top of the mountain? Explain.
2)if a grandfather clock is running slow, how could we adjust the length of the pendulum to correct the time?
3)Explain (a) how it is possible for a large force to produce only a small, or even zero, torque, and (b) how it is possible for a small force to produce a large torque.
1) No
Explanation:
The period of a pendulum is given by
[tex]T=2\pi \sqrt{\frac{L}{g}}[/tex]
where
L is the length of the pendulum
g is the acceleration due to gravity
The value of g, acceleration due to gravity, is not exactly the same in all locations of the Earth. In fact, its value is given by
[tex]g=\frac{GM}{r^2}[/tex]
where G is the gravitational constant, M is the Earth's mass, and r the distance of the point from the Earth's center. This means that at the top of a mountain, r is slightly larger than at the Earth's surface, so the value of g is slightly smaller at the top of the mountain, and therefore the period of the pendulum will also be different (it will be slightly longer than at Earth's surface).
2) We need to decrease the length of the pendulum
Again, the period is given by
[tex]T=2\pi \sqrt{\frac{L}{g}}[/tex] (1)
If the clock is running slow, it means that its period T' is slightly longer than the expected period T: so, we need to shorten the period.
From eq.(1), we see that the period is proportional to the square root of the length of the pendulum, L: therefore, if the length increases the period increases, and if the length decreases, the period will decreases.
Here we want to shorten the period: therefore, according to the equation, we need to decrease the length of the pendulum.
3)
The torque of a force applied is given by
[tex]\tau = Fd sin \theta[/tex]
where
F is the magnitude of the force
d is the distance between the point of application of the force and the pivot point
[tex]\theta[/tex] is the angle between the direction of the force and d
So we have:
a) If we have a large force F, it is possible to produce a small torque by decreasing d, so by applying the force really close to the pivot, or by decreasing [tex]\theta[/tex], which means applying the force as more parallel as possible to d. The torque will be even zero if d=0 (force applied at the pivot point) or if [tex]\theta=0^{\circ}[/tex] (force parallel to d)
b) if we have a small force F, it is possible to produce a large torque by increasing d, so by applying the force really far to the pivot, or by increasing [tex]\theta[/tex], which means applying the force as more perpendicular as possible to d.
If a pendulum clock is accurate at the base of a mountain, it may not be accurate at the top because gravity is weaker at higher altitudes. To adjust a slow grandfather clock, shorten the pendulum. Torque depends on both force and its application point, so large forces can produce small torques and small forces can produce large torques.
1) If a pendulum clock keeps perfect time at the base of a mountain, it may not keep perfect time at the top due to a slight variation in the acceleration due to gravity. A pendulum clock's timing depends on gravity, and at higher altitudes, gravity is slightly weaker which would affect the clock's accuracy.
2) If a grandfather clock is running slow, the length of the pendulum needs to be shortened to increase the rate at which the pendulum swings, thereby correcting the time.
3) (a) A large force can produce a small or zero torque if the force is applied directly along the line of action of the pivot point, as torque is a measure of rotational force and depends on both the amount of force applied and its distance from the pivot.
(b) A small force can produce a large torque if applied at a large distance from the pivot point, as torque is the product of the force and the perpendicular distance from the pivot - thus, even a small force can create significant torque if applied far enough away from the pivot.
For a pendulum clock moved to a location with greater gravity, you would need to shorten the pendulum to maintain the same period and keep correct time.
In summer, the pendulum of a clock generally expands due to heat, which makes the clock run slower, while in winter, it would contract and make the clock run faster.
(Please Help, Will Give BRAINLIEST Answer)
A 50.0-kilogram skydiver jumps from an airplane and is in freefall for 20 seconds.
Immediately before she opens her parachute, her kinetic energy is 78,400 joules.
If the amount of heat her motion transferred to her surroundings during freefall was 884,000 joules, how far did she fall during her freefall?
(Assume the skydiver's gravitational potential energy is only transformed into heat and kinetic energy, and assume the rate of acceleration due to Earth's gravity is 9.81 m/s/s.)
A. 1,960 meters
B. 1,560 meters
C. 9,620 meters
Answer:
A
Explanation:
Initial gravitational energy = final kinetic energy + heat
mgh = KE + Q
(50 kg) (9.81 m/s²) h = 78400 J + 884000 J
h = 1960 meters
What is the energy of a photon that has the same wavelength as an electron having a kinetic energy of 15 ev?
Answer: [tex]6.268(10)^{-16}J[/tex]
Explanation:
The kinetic energy of an electron [tex]K_{e}[/tex] is given by the following equation:
[tex]K_{e}=\frac{(p_{e})^{2} }{2m_{e}}[/tex] (1)
Where:
[tex]K_{e}=15eV=2.403^{-18}J=2.403^{-18}\frac{kgm^{2}}{s^{2}}[/tex]
[tex]p_{e}[/tex] is the momentum of the electron
[tex]m_{e}=9.11(10)^{-31}kg[/tex] is the mass of the electron
From (1) we can find [tex]p_{e}[/tex]:
[tex]p_{e}=\sqrt{2K_{e}m_{e}}[/tex] (2)
[tex]p_{e}=\sqrt{2(2.403^{-18}J)(9.11(10)^{-31}kg)}[/tex]
[tex]p_{e}=2.091(10)^{-24}\frac{kgm}{s}[/tex] (3)
Now, in order to find the wavelength of the electron [tex]\lambda_{e}[/tex] with this given kinetic energy (hence momentum), we will use the De Broglie wavelength equation:
[tex]\lambda_{e}=\frac{h}{p_{e}}[/tex] (4)
Where:
[tex]h=6.626(10)^{-34}J.s=6.626(10)^{-34}\frac{m^{2}kg}{s}[/tex] is the Planck constant
So, we will use the value of [tex]p_{e}[/tex] found in (3) for equation (4):
[tex]\lambda_{e}=\frac{6.626(10)^{-34}J.s}{2.091(10)^{-24}\frac{kgm}{s}}[/tex]
[tex]\lambda_{e}=3.168(10)^{-10}m[/tex] (5)
We are told the wavelength of the photon [tex]\lambda_{p}[/tex] is the same as the wavelength of the electron:
[tex]\lambda_{e}=\lambda_{p}=3.168(10)^{-10}m[/tex] (6)
Therefore we will use this wavelength to find the energy of the photon [tex]E_{p}[/tex] using the following equation:
[tex]E_{p}=\frac{hc}{lambda_{p}}[/tex] (7)
Where [tex]c=3(10)^{8}m/s[/tex] is the spped of light in vacuum
[tex]E_{p}=\frac{(6.626(10)^{-34}J.s)(3(10)^{8}m/s)}{3.168(10)^{-10}m}[/tex]
Finally:
[tex]E_{p}=6.268(10)^{-16}J[/tex]
Scientists have recently discovered one the smallest stars on record. How long will this star last
compared to a larger star formed at the same time?
O A. The smaller star will last longer than the larger star because it has a smaller chance of getting hit by an
asteroid
O B. The smaller star will last longer than the larger star because it burns less fuel.
O C. The larger star will last longer than the smaller star because it uses fuel more efficiently.
O D. The larger star will last longer than the smaller star because it attracts more nebulae
Answer:
The correct answer is B.
Explanation:
Stars start their lives being dense clouds of gas and dust. After a star is formed, it begins to burn hydrogen and transform it into helium. Once the hydrogen is depleted, new stages of nuclear combustion begin, such as burning helium to obtain heavier elements. This stage is shorter in larger stars since the greater the mass of a star, the greater the temperature in its nucleus and the greater the rate of fusion of hydrogen into helium, with which the fuel is depleted more quickly.
Have a nice day!
Scientists have recently discovered one the smallest stars on record. How long will this star last compared to a larger star formed at the same time is B. The smaller star will last longer than the larger star because it burns less fuel.
What is the starsThe length of time a star can live is mainly decided by how much mass it has. Smaller stars weigh less and therefore use up their fuel more slowly than bigger stars. This means that smaller stars can live longer because they use fuel at a slower rate.
The amount of fuel, usually hydrogen, in a star determines how long it can keep producing energy through nuclear fusion. Smaller stars have cooler centers and lower pressure, so they can burn fuel more slowly and efficiently. As a result, they can live much longer than bigger stars.
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Why is there convection in the outer core and what is the result of this?
Answer:
re believed to influence the Earth's magnetic field. ... As heat is transferred outward toward the mantle, the net trend is for the inner boundary of the liquid region to freeze, causing the solid inner core to grow
Explanation:
Final answer:
Convection in the Earth's outer core, caused by heat from radioactive decay and Earth's cooling, leads to the movement of conductive materials like iron and nickel. These movements generate the Earth's magnetic field, essential for maintaining our atmosphere and conditions favorable for life.
Explanation:
Convection in the Earth's outer core is driven by the heat generated from the decay of radioactive elements and the cooling of the Earth's interior. This heat causes the liquid iron and nickel in the outer core to move in convective currents. As these substances are metallic and thus conductive at the high temperatures and pressures found in the core, their movement generates the Earth's magnetic field. This magnetic field is crucial for maintaining the atmosphere and the conditions necessary for life on Earth. Without the convection in the outer core and the resulting magnetic field, Earth might lose essential gases in its atmosphere, similarly to what happened on Mars.
A drunk guy walking on a narrow lane takes 8 steps forward and 6 steps backward and so on.
Each step is 1m long and he requires 1 second to travel. The time that the drunk guy takes to fall in a pit 18m away from the starting point is
a) 18s
b) 126s
c) 78s
d) 62s
Answer: 126 secs
Explanation: he gains 2 steps every time and it takes 9 2 steps to reach 18 meters so what u do is take that 9 and multiply it to 14 (8+6) giving u ur answer of 126 secs.
A 0.80-μm-diameter oil droplet is observed between two parallel electrodes spaced 11 mm apart. The droplet hangs motionless if the upper electrode is 17.8 V more positive than the lower electrode. The density of the oil is 885kg/m3. Part A What is the droplet's mass? Express your answer to two significant figures and include the appropriate units. m m = nothing nothing Request Answer Part B What is the droplet's charge? Express your answer to two significant figures and include the appropriate units. q q = nothing nothing Request Answer Part C Does the droplet have a surplus or a deficit of electrons? How many? Does the droplet have a surplus or a deficit of electrons? How many? deficit 9 electrons surplus 9 electrons surplus 16 electrons deficit 7 electrons
A) [tex]2.4\cdot 10^{-16}kg[/tex]
The radius of the oil droplet is half of its diameter:
[tex]r=\frac{d}{2}=\frac{0.80 \mu m}{2}=0.40 \mu m = 0.4\cdot 10^{-6}m[/tex]
Assuming the droplet is spherical, its volume is given by
[tex]V=\frac{4}{3}\pi r^3 = \frac{4}{3}\pi (0.4\cdot 10^{-6} m)^3=2.68\cdot 10^{-19} m^3[/tex]
The density of the droplet is
[tex]\rho=885 kg/m^3[/tex]
Therefore, the mass of the droplet is equal to the product between volume and density:
[tex]m=\rho V=(885 kg/m^3)(2.68\cdot 10^{-19} m^3)=2.4\cdot 10^{-16}kg[/tex]
B) [tex]1.5\cdot 10^{-18}C[/tex]
The potential difference across the electrodes is
[tex]V=17.8 V[/tex]
and the distance between the plates is
[tex]d=11 mm=0.011 m[/tex]
So the electric field between the electrodes is
[tex]E=\frac{V}{d}=\frac{17.8 V}{0.011 m}=1618.2 V/m[/tex]
The droplet hangs motionless between the electrodes if the electric force on it is equal to the weight of the droplet:
[tex]qE=mg[/tex]
So, from this equation, we can find the charge of the droplet:
[tex]q=\frac{mg}{E}=\frac{(2.4\cdot 10^{-16}kg)(9.81 m/s^2)}{1618.2 V/m}=1.5\cdot 10^{-18}C[/tex]
C) Surplus of 9 electrons
The droplet is hanging near the upper electrode, which is positive: since unlike charges attract each other, the droplet must be negatively charged. So the real charge on the droplet is
[tex]q=-1.5\cdot 10^{-18}C[/tex]
we can think this charge has made of N excess electrons, so the net charge is given by
[tex]q=Ne[/tex]
where
[tex]e=-1.6\cdot 10^{-19}C[/tex] is the charge of each electron
Re-arranging the equation for N, we find:
[tex]N=\frac{q}{e}=\frac{-1.5\cdot 10^{-18}C}{-1.6\cdot 10^{-19}C}=9.4 \sim 9[/tex]
so, a surplus of 9 electrons.
When the flashlight is in the air and the refracted ray enters the water, how does the angle of refraction compare with the angle of incidence?
Answer:
The refracted angle will be less than the angle of incidence and the speed of light is slower in the new medium (which is water) and is closer to the normal.
Try remembering this by using FST SFA (Fast Sofa)
Fast -> Slow = Towards the normal
Slow -> Fast = Away from normal
When the flashlight is in the air and the refracted ray enters the water, the angle of refraction will be less than the angle of incidence.
What is refracted ray?When the light ray falls on the surface with angle of incidence, the lights gets reflected in the same medium with angle of reflection. The remaining rays gets into the medium on the other side of the surface.
The refracted angle is always less than the angle of incidence and the speed of light is slower comparatively in the another medium.
Thus, when the flashlight is in the air and the refracted ray enters the water, the angle of refraction will be less than the angle of incidence.
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What is the energy of a photon that has the same wavelength as an electron having a kinetic energy of 15 ev?
Answer: [tex]6.268(10)^{-16}J[/tex]
The kinetic energy of an electron [tex]K_{e}[/tex] is given by the following equation:
[tex]K_{e}=\frac{(p_{e})^{2} }{2m_{e}}[/tex] (1)
Where:
[tex]K_{e}=15eV=2.403^{-18}J=2.403^{-18}\frac{kgm^{2}}{s^{2}}[/tex]
[tex]p_{e}[/tex] is the momentum of the electron
[tex]m_{e}=9.11(10)^{-31}kg[/tex] is the mass of the electron
From (1) we can find [tex]p_{e}[/tex]:
[tex]p_{e}=\sqrt{2K_{e}m_{e}}[/tex] (2)
[tex]p_{e}=\sqrt{2(2.403^{-18}J)(9.11(10)^{-31}kg)}[/tex]
[tex]p_{e}=2.091(10)^{-24}\frac{kgm}{s}[/tex] (3)
Now, in order to find the wavelength of the electron [tex]\lambda_{e}[/tex] with this given kinetic energy (hence momentum), we will use the De Broglie wavelength equation:
[tex]\lambda_{e}=\frac{h}{p_{e}}[/tex] (4)
Where:
[tex]h=6.626(10)^{-34}J.s=6.626(10)^{-34}\frac{m^{2}kg}{s}[/tex] is the Planck constant
So, we will use the value of [tex]p_{e}[/tex] found in (3) for equation (4):
[tex]\lambda_{e}=\frac{6.626(10)^{-34}J.s}{2.091(10)^{-24}\frac{kgm}{s}}[/tex]
[tex]\lambda_{e}=3.168(10)^{-10}m[/tex] (5)
We are told the wavelength of the photon [tex]\lambda_{p}[/tex] is the same as the wavelength of the electron:
[tex]\lambda_{e}=\lambda_{p}=3.168(10)^{-10}m[/tex] (6)
Therefore we will use this wavelength to find the energy of the photon [tex]E_{p}[/tex] using the following equation:
[tex]E_{p}=\frac{hc}{lambda_{p}}[/tex] (7)
Where [tex]c=3(10)^{8}m/s[/tex] is the speed of light in vacuum
[tex]E_{p}=\frac{(6.626(10)^{-34}J.s)(3(10)^{8}m/s)}{3.168(10)^{-10}m}[/tex]
Finally:
[tex]E_{p}=6.268(10)^{-16}J[/tex]
The energy of a photon is about 6.3 × 10⁻¹⁶ Joule
[tex]\texttt{ }[/tex]
Further explanationThe term of package of electromagnetic wave radiation energy was first introduced by Max Planck. He termed it with photons with the magnitude is :
[tex]\large {\boxed {E = h \times f}}[/tex]
E = Energi of A Photon ( Joule )
h = Planck's Constant ( 6.63 × 10⁻³⁴ Js )
f = Frequency of Eletromagnetic Wave ( Hz )
[tex]\texttt{ }[/tex]
The photoelectric effect is an effect in which electrons are released from the metal surface when illuminated by electromagnetic waves with large enough of radiation energy.
[tex]\large {\boxed {E = \frac{1}{2}mv^2 + \Phi}}[/tex]
[tex]\large {\boxed {E = qV + \Phi}}[/tex]
E = Energi of A Photon ( Joule )
m = Mass of an Electron ( kg )
v = Electron Release Speed ( m/s )
Ф = Work Function of Metal ( Joule )
q = Charge of an Electron ( Coulomb )
V = Stopping Potential ( Volt )
Let us now tackle the problem !
[tex]\texttt{ }[/tex]
Given:
kinetic energy of an electron = Ek = 15 eV = 2.4 × 10⁻¹⁸ Joule
Asked:
energy of photon = E = ?
Solution:
Firstly , we will use the formula of kinetic energy:
[tex]Ek = \frac{1}{2}mv^2[/tex]
[tex]v^2 = \frac{2Ek}{m}[/tex]
[tex]v = \sqrt{ \frac{2Ek}{m}}[/tex]
[tex]\texttt{ }[/tex]
Next , we will use the formula of The Broglie's Wavelength:
[tex]\lambda = \frac{h}{mv}[/tex]
[tex]\lambda = \frac{h}{m\sqrt{2Ek/m}}[/tex]
[tex]\lambda = \frac{h}{\sqrt{2mEk}}[/tex]
[tex]\texttt{ }[/tex]
[tex]E = h f[/tex]
[tex]E = h \frac{c}{\lambda}[/tex]
[tex]E = h \frac{c}{\frac{h}{\sqrt{2mEk}}}[/tex]
[tex]E = c\sqrt{2mEk}[/tex]
[tex]E = 3 \times 10^8 (\sqrt{2(9.11 \times 10^{-31} \times 2.4 \times 10^{-18}}[/tex]
[tex]E \approx 6.3 \times 10^{-16} \texttt{ Joule}[/tex]
[tex]\texttt{ }[/tex]
Learn morePhotoelectric Effect : https://brainly.com/question/1408276Statements about the Photoelectric Effect : https://brainly.com/question/9260704Rutherford model and Photoelecric Effect : https://brainly.com/question/1458544[tex]\texttt{ }[/tex]
Answer detailsGrade: College
Subject: Physics
Chapter: Quantum Physics
[tex]\texttt{ }[/tex]
Keywords: Quantum , Physics , Photoelectric , Effect , Threshold , Wavelength , Stopping , Potential , Copper , Surface , Ultraviolet , Light
By what factor does the peak frequency change if the celsius temperature of an object is doubled from 20.0 ∘c to 40.0 ∘c?
Answer:
it increases by a factor 1.07
Explanation:
The peak wavelength of an object is given by Wien's displacement law:
[tex]\lambda=\frac{b}{T}[/tex] (1)
where
b is the Wien's displacement constant
T is the temperature (in Kelvins) of the object
given the relationship between frequency and wavelength of an electromagnetic wave:
[tex]f=\frac{c}{\lambda}[/tex]
where c is the speed of light, we can rewrite (1) as
[tex]\frac{c}{f}=\frac{b}{T}\\f=\frac{Tc}{b}[/tex]
So the peak frequency is directly proportional to the temperature in Kelvin.
In this problem, the temperature of the object changes from
[tex]T_1 = 20.0^{\circ}+273=293 K[/tex]
to
[tex]T_2 = 40.0^{\circ}+273 = 313 K[/tex]
so the peak frequency changes by a factor
[tex]\frac{f_2}{f_1} \propto \frac{T_2}{T_1}=\frac{313 K}{293 K}=1.07[/tex]
How many days does it take for mercury to orbit the sun
It takes approximately 88 Earth days for Mercury to orbit the sun.
Hope I helped, sorry if I'm wrong ouo.
~Potato
Copyright Potato 2019.
Answer:
87.96926 Days =88 days
Explanation:
Average speed 105,947 miles per hour.
Please help on this one?
Answer: d
Explanation:
When an atom gains an electron it becomes
Answer:
it will become a negatively charged ion
Explanation:
Please help on this one?
Answer:
D. An image that is smaller than the object and is behind the mirror
Energy from the sun reaches earth mostly by
Answer:
Radiation is the correct answer for this question.
Explanation:
Which phenomenon can only be explained by assuming that light is quantized
Light can be considered as a wave or as particles, in this context Einstein proposed that light behaves like a stream of particles called photons with an energy, in order to correctly explain the photoelectric effect.
This fenomenom consists in the emission of electrons (electric current) that occurs when light falls on a metal surface under certain conditions.
So, if we consider light as a stream of photons and each of them has energy, this energy is able to pull an electron out of the crystalline lattice of the metal and communicate, in addition, a kinetic energy.
This means the photoelectric effect can only be explained based on the corpuscular model of light, that is, light is quantized.
A sealed bottle is full of air. The volume of the bottle is decreased, but the temperature remains constant. What other change occurs in the bottle?
Answer:
The air pressure will increase.
Explanation:
Answer:The pressure of the gas in the bottle increases
Explanation:this is governed by Boyles law which states that at constant temperature,the volume of a gas is inversely proportional to it's pressure ,i.e mathematically V&1/P at constant temperature,this can be further arranged as P1V1=P2V2.the implication of this formula is that as volume of gases increases,it pressure is decreasing and vice versa.
It is important to note that the constant here is the absolute temperature of the bottle
Two hundred grams of liquid A is at a temperature of 100◦C. One hundred grams of liquid B is at a temperature of 0◦C. When the two liquids are mixed, the final temperature is 50◦C. Which material has a higher specific heat? 1. The specific heat of A is greater than that of B. 2. The specific heat of A is great than B if its viscosity is greater. 3. The specific heats of A and B are equal. 4. The specific heat cannot be defined when fluids are mixed in this way. 5. The specific heat of B is greater than that of A. "correct"
Answer:
The specific heat of B is greater than that of A.
Explanation:
The amount of heat lost by A is:
q = m C ΔT
q = (200 g) Ca (100°C - 50°C)
q = 10,000 Ca
The amount of heat gained by B is:
q = (100 g) Cb (50°C - 0°C)
q = 5,000 Cb
Since the heat lost by A = heat gained by B:
10,000 Ca = 5,000 Cb
2 Ca = Cb
So the heat capacity of B is double the heat capacity of A. Answer 5.
Taking into account the definition of calorimetry, the correct answer is option 5: The specific heat of B is greater than that of A.
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).
So, the equation that allows to calculate heat exchanges is:
Q = c× m× ΔT
where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.
In this case, you know:
For liquid A: Mass= 200 g Initial temperature= 100 °C Final temperature= 50 ºC Specific heat = [tex]c_{A}[/tex] For liquid B: Mass of water = 100 g Initial temperature of water= 0 ºC Final temperature of water= 50 ºC Specific heat of water = [tex]c_{B}[/tex]Replacing in the expression to calculate heat exchanges:
For liquid A: QliquidA= [tex]c_{A}[/tex] × 200 g× (50 C - 100 C)
For liquid B: QliquidB= [tex]c_{B}[/tex] × 100 g× (50 C - 0 C)
If two isolated bodies or systems exchange energy in the form of heat, the quantity received by one of them is equal to the quantity transferred by the other body. That is, the total energy exchanged remains constant, it is conserved.
Then, the heat that the liquid A gives up will be equal to the heat that the liquid B receives. Therefore:
- QliquidA = + QliquidB
- [tex]c_{A}[/tex] × 200 g× (50 C - 100 C)= [tex]c_{B}[/tex] × 100 g× (50 C - 0 C)
Solving:
- [tex]c_{A}[/tex] × 200 g× ( - 50 C)= [tex]c_{B}[/tex] × 100 g× (50 C)
[tex]c_{A}[/tex] × 10,000 gC= [tex]c_{B}[/tex] × 5,000 gC
([tex]c_{A}[/tex] × 10,000 gC) ÷ 5,000 gC= [tex]c_{B}[/tex]
[tex]c_{A}[/tex] × 2= [tex]c_{B}[/tex]
Finally, the correct answer is option 5: The specific heat of B is greater than that of A.
Learn more:
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The weight of an object is the product of its mass, m, and the acceleration of gravity, g (where g=9.8 m/s2). Of an object’s mass is m=10. kg, what is its weight?
Answer:
98 N
Explanation:
The weight of an object is given by
W = mg
where
m is the mass of the object
g = 9.8 m/s^2 is the acceleration of gravity
Here we have an object with mass
m = 10 kg
Therefore, its weight will be
[tex]W=(10 kg)(9.8 m/s^2)=98 N[/tex]
Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.
Answer:
- Distance is a scalar quantity, defined as the total amount of space covered by an object while moving between the final position and the initial position. Therefore, it depends on the path the object has taken: the distance will be minimum if the object has travelled in a straight line, while it will be larger if the object has taken a non-straight path.
- Displacement is a vector quantity, whose magnitude is equal to the distance (measured in a straight line) between the final position and the initial position of the object. Therefore, the displacement does NOT depend on the path taken, but only on the initial and final point of the motion.
If the object has travelled in a straight path, then the displacement is equal to the distance. In all other cases, the distance is always larger than the displacement.
A particular case is when an object travel in a circular motion. Assuming the object completes one full circle, we have:
- The distance is the circumference of the circle
- The displacement is zero, because the final point corresponds to the initial point
An elevator filled with passengers has a mass of 1700 kg. (a) The elevator accelerates upward from rest at a rate of 1.20 m/s^{2} 2 for 1.50 s. Calculate the tension in the cable supporting the elevator. (b) The elevator continues upward at constant velocity for 8.50 s. What is the tension in the cable during this time? (c) The elevator decelerates at a rate of 0.600 m/s^{2} 2 for 3.00 s. What is the tension in the cable during deceleration? (d) How high has the elevator moved above its original starting point, and what is its final velocity?
(a) 18717 N
Newton's second law in this situation can be written as:
[tex]\sum F = T-W = ma[/tex] (1)
where
T is the tension in the cable, pointing upward
W is the weight of the elevator+passengers, pointing downward
m is the mass of the elevator+passengers (1700 kg)
a is the acceleration of the system (1.20 m/s^2, upward)
The weight is equal to the product between the mass, m, and the gravitational acceleration, g:
[tex]W=mg=(1700 kg)(9.81 m/s^2)=16,677 N[/tex]
So now we can solve eq.(1) to find T, the tension in the cable:
[tex]T=W+ma=16,677 N +(1700 kg)(1.20 m/s^2)=18,717 N[/tex]
(b) 16677 N
In this situation, the elevator is moving with constant velocity: this means that its acceleration is zero,
a = 0
So Newton's second law becomes
[tex]\sum F = T-W = 0[/tex]
and so we find
[tex]T=W=16,677 N[/tex]
(c) 15657 N
During the deceleration phase, Newton's second law can be written as:
[tex]\sum F = T-W = ma[/tex] (1)
Where the acceleration here points downward (because the elevator is decelerating), as the weight W, so we can write it as a negative number:
a = -0.600 m/s^2
we can solve the equation to find T, the tension in the cable:
[tex]T=W+ma=16,677 N +(1700 kg)(-0.600 m/s^2)=15,657 N[/tex]
(d) 19.35 m, 0 m/s
Distance covered during the first part of the motion; we know that
u = 0 is the initial velocity
a = 1.20 m/s^2 is the acceleration
t = 1.50 s is the time
So the distance covered is given by
[tex]d_1=ut + \frac{1}{2}at^2 = (0)(1.50 s)+\frac{1}{2}(1.20 m/s^2)(1.50 s)^2=1.35 m[/tex]
and the final velocity after this phase is
[tex]v_1=u+at=0+(1.20 m/s^2)(1.50 s)=1.8 m/s[/tex]
During the 2nd part of the motion, the elevator moves at constant speed of 1.8 m/s for t=8.50 s, so the distance covered here is
[tex]d_2 = v_1 t =(1.8 m/s)(8.50 s)=15.3 m[/tex]
Finally, in the third part the elevator decelerates at a = -0.600 m/s^2 for t = 3.00 s. So, the distance covered here is
[tex]d_3 = v_1 t + \frac{1}{2}at^2=(1.8 m/s)(3.00 s) + \frac{1}{2}(-0.600 m/s^2)(3.00 s)^2=2.7 m[/tex]
and the final velocity is
[tex]v_3 = v_1 +at = 1.8 m/s +(-0.600 m/s^2)(3.00 s)=0[/tex]
and the total distance covered is
[tex]d=d_1 +d_2+d_3=1.35 m+15.30 m+2.70 m=19.35 m[/tex]
Place the tiles in the correct order to describe how a nuclear power plant generates power.
1). Radioactive decay produces heat. 2). Boiling water produces steam. 3). Steam spins turbines. 4). Electricity is generated.
Answer:
The order is:
Radioactive decay produces heat.
Boiling water produces steam.
Steam spins turbines.
Electricity is generated.
Explanation:
A nuclear power plant uses heat from nuclear reactions to create steam from water. This steam spins turbines, which generate electricity.
Explanation:A nuclear power plant produces electricity using the heat generated by the nuclear reactions or radioactive decay within the reactor. The heat generated through this process is used to heat water, forming steam. Following this, in order:
Radioactive decay in the reactor produces intense heat.This heat is used to boil water, converting it into steam.The high-pressure steam is directed at turbines, causing them to spin.This mechanical energy from the spinning turbines is converted into electrical energy or electricity.Learn more about Nuclear Power Production here:https://brainly.com/question/34702905
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Read the scenario.
A pinecone is lying on the road at a position of 0 m. Floyd kicks it to a position of 4 m west. Then, Sybil kicks it, and it comes to rest at a position of 2 m west.
Which option represents a scalar quantity from the scenario?
displacement = 2 m west
distance = 2 m
distance = 6 m west
distance = 6 m
Answer:
distance = 6 m
Explanation:
- Distance is a scalar quantity (so, only magnitude, no direction), and it is calculated as the scalar sum of all the distances travelled by an object during its motion, regardless of the direction. So, in this problem, the distance covered by the pinecone is
d = 4 m + 2 m = 6 m
- Displacement is a vector quantity (magnitude+direction), and its magnitude is calculate as the distance in a straight line between the final position and the initial position of the object. In this case, the final position is 2 m west and the initial position is 0 m, so the displacement of the pinecone is
d = 2 m west - 0 m = 2 m west
So, a scalar quantity from this scenario is
distance = 6 m
What is the most common fuel used in nuclear power plants
Answer:
Uranium
Explanation:
The nuclear power plants on Earth work based on the principle of nuclear fission.
Nuclear fission occurs when a heavy unstable nucleus splits into lighter nuclei: in this process, the total mass of the final product is smaller than the mass of the initial heavy nucleus, so part of the mass is converted into energy according to Einstein's equation:
[tex]E=mc^2[/tex]
where E is the energy released when an amount of mass m is converted (c is the speed of light).
Generally, the "fuel" (the initial heavy unstable element) used in nuclear power plants is uranium. A nucleus of uranium is bombarded with slow neutrons, which cause the process of nuclear fission to start: the nucleus of uranium split into lighter nuclei, releasing also additional neutrons, which are used to start further nuclear reactions.