Answer: The universe is not infinite in space
This question is known as the Olbers' Paradox, who in the 19th century posed a question similar to the following:
If the universe where we live is infinite, static, and uniformly populated with stars (similar to the distribution of trees in an immense forest where we would find a tree in whatever direction we observe), which have eternally existed; the light of all of them would intensely illuminate any point of space.
That is to say, we should see stars in any direction, no matter how far away they are and the celestial vault should be exaggeratedly bright.
But this is not the case, the night sky is dark and the universe too.
Why?
Well, although the standard cosmological model of the universe suggests that it is infinite, the observable universe is not.
In other words, the universe is finite.
Then, in a universe of limited size, even having a great quantity of stars and galaxies, all of them would not be enough to illuminate all the space.
In addition, there is another important point: Not only the universe is finite, also its age is; this means it had a beginning.
Hence, having a finite observable universe that is continuously expanding, distant stars and galaxies move away even further.
So, when we look at a star that is 1 million light years away, we are seeing the star as it was seen 1 million years ago.
This means that the amount of light that comes to us from distant stars decreases all the time.
Therefore the light from the most distant stars has not yet had enough time to reach us.
Answer:
It is B.
Explanation:
A sparrow eats 1200 j of seeds. of this, 425 j is eliminated as feces and 750 j are used in cellular respiration. what is the approximate production efficiency of this animal?
Answer:
0.625 (62.5 %)
Explanation:
The production efficiency is equal to the rate between the energy converted into useful energy and the energy in input:
[tex]\eta = \frac{E_{useful}}{E_{in}}[/tex]
where in this case:
- the useful energy is 750 J (the energy used in cellular respiration)
- the energy in input is 1200 J (the energy taken by eating the seeds)
Substituting,
[tex]\eta = \frac{750 J}{1200 J}=0.625[/tex]
Which means an approximate efficiency of 62.5 %.
If you want to double the kinetic energy of a gas molecule, by what factor must you increase its momentum?
A) 16
B) √2
C) 2
D) 2√2
E) 4
The correct answer is B)
Final answer:
To double the kinetic energy of a gas molecule, the momentum must be increased by a factor of square root of 2 (B) √2.
Explanation:
If you want to double the kinetic energy of a gas molecule, by what factor must you increase its momentum, the answer is B) √2. Kinetic energy (KE) is given by the equation KE = ½mv², where m is the mass and v is the velocity of the molecule. Since momentum (p) is the product of mass and velocity (p = mv), we can express kinetic energy in terms of momentum as KE = p² / (2m).
Therefore, to double the kinetic energy (2KE), the equation becomes 2(½mv²) = mv², which implies that the new momentum (p') squared would be twice the original momentum squared (2p²). Taking the square root on both sides results in p' = p√2, so the momentum must be increased by a factor of the square root of 2 to double the kinetic energy of the molecule.
Which scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei?
Ernest Rutherford was a British physicist and chemist of New Zealand origin, who conducted a series of experiments together with Hans Geiger and Ernest Marsden; where the result led him to propose a new atomic model.
It should be noted that at that time, the "accepted" atomic model was Thomson's raisin pudding atomic model (electrons with negative charge immersed an the atom of positive charge that counteracted the negative charge of the electrons, like raisings embedded in a pudding), who discovered the electron and formerly was a professor of Rutherford.
Now, the experiment conducted under the direction of Ruherford at the laboratories of the University of Manchester during the year 1911; was for the purpose of corroborating Thomson's atomic model. To achieve this, a thin metal sheet was bombarded with alpha particles (nuclei of helium gas).
The idea was that these alpha particles, having positive electric charge, were attracted by the atom's negative charges and repelled by the positive charges, and it was expected that they would pass through the thin sheet without hardly deviating. Then, to observe the crash site of the particle, a phosphorescent screen was placed behind and on the sides of the metal sheet.
For according to Thomson's atomic model the positive and negative charges were evenly distributed, the sphere (the atom) had to be electrically neutral, and the alpha particles would pass through the sheet without deviating.
However, the results were surprising:
As expected, most of the particles went through the sheet without deviating.
But some suffered large deviations and, most importantly, a small number of particles bounced backwards.
That is:
The alpha particle beam was scattered (repelled) when it hit the thin metal sheet.
These facts could not be explained by Thomson's atomic model, so Rutherford developed another, suggesting that:
There is a concentration of charge in the center of the atom (which was later called nucleus) surrounded by electrons.
This new model could explain the proven fact in his experiments that some particles bounced in the direction opposite to the incident particles, because the electrical charge of this nucleus was positive, equal to the electrical charge of the alpha particles.
This is how Rutherford proposed a new atomic model and discovered the existence of the nucleus. However, this was not the definitive model, because on 1913 it was replaced by Bohr's.
Please help on this one?
Using the given equation you get:
E = 1.99x10^-25 / 9.0x10^-6
Divide 1.99 by 9.0: 1.99/9.0 = 0.22
For the scientific notation, when dividing subtract the two exponents:
25 -6 = 19
So you now have 0.22 x 10^-19
Now you need to change the 0.22 to be in scientific notation form:
2.2 x 10^-20
The answer is B.
Two forces with magnitudes of 25 and 30 pounds act on an object at angles of 10° and 100° respectively. Find the direction and magnitude of the resultant force. Round to two decimal places in all intermediate steps and in your final answer.
Answer:
39.05 pounds at [tex]60.19^{\circ}[/tex]
Explanation:
To find the resultant force, we need to decompose each vector along the x- and y- directions. Let's do it:
Vector 1:
[tex]A_x = 25 \cdot cos 10^{\circ}=24.62[/tex]
[tex]A_y = 25 \cdot sin 10^{\circ}=4.34[/tex]
Vector 2:
[tex]B_x = 30 \cdot cos 100^{\circ}=-5.21[/tex]
[tex]B_y = 30 \cdot sin 100^{\circ}=29.54[/tex]
Resultant components:
[tex]R_x = A_x + B_x =24.62+(-5.21)=19.41[/tex]
[tex]R_y = A_y + B_y = 4.34+29.54 =33.88[/tex]
So the magnitude of the resultant is
[tex]R=\sqrt{R_x^2+R_y^2}=\sqrt{(19.41)^2+(33.88)^2}=39.05[/tex]
And the direction is
[tex]\theta=tan^{-1}(\frac{R_y}{R_x})=tan^{-1}(\frac{33.88}{19.41})=60.19^{\circ}[/tex]
The resultant force is found by summing the horizontal and vertical components of the two forces and then calculating the magnitude and direction of the resultant vector using the Pythagorean theorem and inverse tangent function respectively.
Explanation:We can calculate the resultant force by breaking down each force into its horizontal and vertical components, summing these components and then calculating the magnitude and direction of the resultant force by applying principles of trigonometry and vector addition.
The first force of 25 pounds can be broken down into its horizontal and vertical components as follows: the horizontal component will be 25*cos(10°) and the vertical component will be 25*sin(10°).
Similarly, the second force of 30 pounds acts at an angle of 100°. Its components will be: the horizontal component as 30*cos(100°), and the vertical component as 30*sin(100°).
Now, the resultant force will have a horizontal component equal to the sum of the horizontal components of the two forces, and a vertical component equal to the sum of the vertical components of the two forces. Therefore, the horizontal and vertical components of the resultant force can be calculated as the sum of the respective components of the individual forces.
The magnitude of the resultant force can then be found by using the Pythagorean theorem, i.e., the square root of the sum of the squares of the horizontal and vertical components of the resultant force. The direction of the resultant force can be found using the inverse tangent function (atan or tan⁻¹) applied to the ratio of the vertical component to the horizontal component of the resultant force.
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The freezing point and the boiling point of water can be altered by a
variety of techniques. Which of the following has little or no effect on the
boiling point of water?
A Increasing the air pressure above the liquid
B Adding alcohol to the water
C Adding sodium chloride to the water
D Increasing the amount of water
Answer:
Option B is ur answer
Answer:
The answer is D
Explanation:
A train is speeding down a railroad track at a speed of 50 miles per hour. From whose reference point is the train not moving?
Passengers on the train, and flies on the passengers, can be sleeping or reading books. In their reference frames, the train is not moving.
The Cosmic Background Radiation Outer space is filled with a sea of photons, created in the early moments of the universe. The frequency distribution of this "cosmic background radiation" matches that of a blackbody at a temperature near 2.7K.What is the peak frequency of this radiation in Hz?What is the wavelength that corresponds to the peak frequency in mm?
A) Peak wavelength: 1.07 mm
The peak wavelength of the Cosmic Background Radiation can be found by using Wien's displacement law:
[tex]\lambda = \frac{b}{T}[/tex]
where
[tex]\lambda[/tex] is the peak wavelength
[tex]b=2.898\cdot 10^{-3}m\cdot K[/tex] is Wien's displacement constant
T is the absolute temperature
For the Cosmic Background Radiation,
T = 2.7 K
So the peak wavelength is
[tex]\lambda = \frac{2.898\cdot 10^{-3}m\cdot K}{2.7 K}=1.07\cdot 10^{-3} m=1.07 mm[/tex]
B) Peak frequency: [tex]2.8\cdot 10^{11}Hz[/tex]
The peak frequency can be found by using the relationship:
[tex]f=\frac{c}{\lambda}[/tex]
where
[tex]c=3.0\cdot 10^8 m/s[/tex] is the speed of light
[tex]\lambda[/tex] is the peak wavelength
Substituting numbers, we find
[tex]f=\frac{3.0\cdot 10^8 m/s}{1.07\cdot 10^{-3} m}=2.8\cdot 10^{11}Hz[/tex]
the fusion of deuterium and hydrogen is shown in the equation. fill in the missing number.
?/1 H + 1/1 H--- 3/2 He + energy
help fast!!!!!
Answer:
= 2
Explanation:
During nuclear fusion, two lighter nuclei of elements combine to form heavy nucleus and also energy is released;
During the process of hydrogen fusion a nucleus of deuterium is formed from two protons with emission of a neutrino.
In this case deuterium fuses with hydrogen nuclei to form helium-3 and also release energy.
That is;
2/1 H + 1/1 H = 3/1 He + energy
5. Define the terms comet, asteroid, and meteoroid.
It is a celestial body constituted by ice, dust and rocks that orbit around the Sun, after having been altered by the Oort cloud; following different trajectories that can be highly eccentric elliptical (periodic trajectories), parabolic or hyperbolic.
One of the main characteristics of a comet is that it travels quite fast, on its way around the Sun and has a long tail, which always go in the opposite direction to the Sun (due to the radiation pressure of sunlight).
Asteroid:
It is a small rocky body (smaller than a planet and larger than a meteoroid). Most of these bodies are orbiting between Mars and Jupiter in the region known as the asteroid belt; while others accumulate at Jupiter's Lagrange points, and others cross the orbits of the planets.
Meteoroid:
It is a fragment of the celestial body that moves through space, which is smaller in size to an asteroid. If it gets to enter the atmosphere of the Earth, it will start to burn by friction with it (combustion) and it will be called a meteor, while if it hits the surface, it will be called a meteorite.
Comets are loose collections of ice, dust, and small rocky particles whose orbits are usually very long and narrow
This is a map that shows hot spots around the world.
Which phrases describe the formation of the Hawaiian Islands? Check all that apply.
formed due to subduction
formed in the middle of a plate
formed at a divergent boundary
formed at a convergent boundary
formed where mantle erupts through crust
Formed where mantle erupts through crust
Answer:
The Hawaiian Islands were formed where mantle erupts through crust.
Explanation:
All the Hawaiian Islands were formed by the action of volcanoes that arose from the bottom of the sea, from a source of magma (hot spot).
Hawaii's hot spot theory holds that the tectonic plate under the Pacific moves, while the hot spot stands still, creating new volcanoes. For this reason, the volcanoes of the southern half of the island of Hawaii remain active today.
The oldest islands have inactive volcanoes, but in the newest ones volcanoes still active. The island of Hawaii has five volcanoes, and one of them is one of the most active in the world, the Kīlauea.
which is an example of acceleration?
a. pickup driving 30 km in 20 minutes
b. ac car slowing down on a sharp curve
c. an airplane traveling 450km/h
d. an 18 wheeler driving west at 50km/h
plz help
Definition
Acceleration is the term used to describe an object that is either speeding up or slowing down.
Explanation
Based on the given answer choices, answer choices A, C, and D does not describe an object either gaining speed or losing speed; however, object B states this. For this reason, answer choice B is the correct answer.
Answer
b. ac car slowing down on a sharp curve
Final answer:
Acceleration is any change in the velocity of an object, which includes speeding up, slowing down, or changing direction. The example of a car slowing down on a sharp curve is a clear illustration of acceleration.
Explanation:
The question: Which is an example of acceleration? involves understanding the concept of acceleration in physics. Acceleration refers to any change in the velocity of an object, which includes speeding up, slowing down, or changing direction. Therefore, the correct answer is b. a car slowing down on a sharp curve. This example perfectly illustrates acceleration because the car is changing its speed (slowing down) as it moves around the curve, which is a change in velocity. The other options, such as a pickup driving a constant distance in a specific time, an airplane traveling at a constant speed, or an 18 wheeler driving west at a constant speed, do not necessarily imply a change in speed or direction, and thus, do not serve as clear examples of acceleration.
The average power dissipated by a resistor connected to a sinusoidal emf is 5.0 W.
a) What is Pavg if the resistance R is doubled?
Pavg=IR2R
Pavg=IR22R ∴=IR2R ∴Pavg=2.5 W
b) What is P_{\rm avg} if the peak emf {\cal{E}}_0 is doubled?
c) What is P_{\rm avg} if both are doubled simultaneously?
The average power if both the resistance and peak emf are doubled simultaneously is 10 W.
a)
The average power is:
[tex]P_{avg}=\frac{(V_{RMS})^2}{R} \\\\[/tex]
If the resistance is doubled. The new average power is:
[tex]P_{avg}'=\frac{(V_{RMS})^2}{2R}=0.5*\frac{(V_{RMS})^2}{R} =0.5*5=2.5\ W\\\\[/tex]
b)
[tex]P_{avg}=\frac{(V_{RMS})^2}{R}= \frac{(E_o/\sqrt{2} )^2}{R} \\\\\\\\[/tex]
If the peak emf is doubled:
[tex]P_{avg}'=\frac{(2E_o/\sqrt{2} )^2}{R}=4*\frac{(E_o/\sqrt{2} )^2}{R}=4*5=20\ W[/tex]
c)
[tex]P_{avg}=\frac{(V_{RMS})^2}{R}= \frac{(E_o/\sqrt{2} )^2}{R} \\\\\\\\[/tex]
If both are doubled simultaneously:
[tex]P_{avg}'=\frac{(2E_o/\sqrt{2} )^2}{2R}=2*\frac{(E_o/\sqrt{2} )^2}{R}=2*5=10\ W[/tex]
The average power if both the resistance and peak emf are doubled simultaneously is 10 W.
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Doubling the resistance halves the average power dissipated to 2.5W. If the peak emf is doubled, the average power becomes four times, which is 20W. If both are doubled simultaneously, Pavg becomes double the initial value, which is 10W.
Explanation:Given, the average power Pavg dissipated by a resistor connected to a sinusoidal emf is 5.0 W. The expression for average power Pavg is given by Pavg = (Irms)^2R.
a) If the resistance R is doubled, the average power Pavg becomes halved, which is 2.5W as per the equation Pavg = (Irms)^22R.
b) If the peak emf E0 is doubled, then the average power becomes four times, as per the equation Pavg = 4*(Irms)^2*R, which means Pavg = 20W.
c) If both resistance R and peak emf E0 are doubled simultaneously, then Pavg doubles from the initial value, because, Pavg = 2*(Irms)^2*2R giving Pavg = 10W
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a piece of styrofoam has a charge of -0.004 and is placed 0.2 m from a piece of salt with a charge of -0.003 c. the resulting electrostatic force is positive. this indicates that
Answer:
the salt has a greater amount of charge
Explanation:
Please help me quickly!
A go-cart has a mass of 90 kg. It moves at a rate of 3 m/s. What is its kinetic energy?
270 J
405 J
810 J
405j because kE=1/2mv^2
Answer: 405 J
Explanation:
i got it right on my exam
An electron is moving directly toward you in a horizontal path when it suddenly enters a uniform magnetic field that is either vertical or horizontal.
If the electron begins to curve upward in its motion just after it enters the field, you can conclude that the direction of the magnetic field is
If the electron begins to curve upward in its motion just after it enters the field, you can conclude that the direction of the magnetic field is
upward.
downward.
to your left.
to your right.
Answer:
To your left
Explanation:
The direction of the force exerted on charged particle due to a magnetic field is given by the right-hand-rule, where:
- The index finger indicates the direction of motion of the electron
- the middle finger gives the direction of the magnetic field
- the thumb gives the direction of the force if the particle is positively charged - otherwise, the direction is reversed
in this case, we have an electron (so, a negatively charged particle):
- The direction of motion (index finger) is horizontal, toward you
- The electron begins to curve upward as it enters the field, so this means that the force exerted on the electrons is upward --> the thumb must point downward (because the electron is negatively charged)
- The index finger gives us the direction of the magnetic field: therefore, to your left.
When the tympanic membrane vibrates with the same frequency as the incoming sound waves it is known asamplitude.pitch.hertz.resonance.cycles.
Resonance is a phenomenon that occurs when a body capable of vibrating is subjected to the action of a periodic force, whose frequency of vibration approaches the characteristic frequency of vibration (called resonance frequence) of said body. This is due a relatively small force applied in a repeated form, causing the amplitude of the oscillating system to become very large.
In other words, for the specific case of sound waves, this phenomenon occurs when the frequency of the wave that is external to the system or body coincides with the resonance frequency (characteristic frequency that reaches the maximum degree of oscillation) of this system or body.
In these circumstances the body vibrates, progressively increasing the amplitude of movement after each successive actions of the force. However, this effect can be destructive in some rigid materials.
What type of circuit is illustrated?
series circuit
short circuit
parallel circuit
open circuit
Answer:
Is a Series Circuit
Explanation:
The circuit shown in the image is a series circuit, is considered as a closed circuit meaning that only has one path for the current to flow with all light bulbs in a row, the voltage applied to the circuit is equal to each voltage drop in the light bulb, if any light bulbs blow out, the current will not flow because the circuit is broken and the remaining light bulb would turn off.
A high school student makes a large pot of hot chocolate for her friends. Once it is warm enough, she pours a little bit of the hot chocolate into a mug so that she can taste it.
Which option correctly assesses the thermal and average kinetic energy in the scenario?
Select all that apply.
The hot chocolate in the large pot and the hot chocolate in the mug have the same amount of average kinetic energy.
The hot chocolate in the large pot has more thermal energy than the hot chocolate in the mug.
The hot chocolate in the large pot and the hot chocolate in the mug have the same amount of thermal energy.
The hot chocolate in the large pot has more average kinetic energy than the hot chocolate in the mug.
the hot chocolate in the large pot has more therma energy than the hot chocolate in the mug
Answer:
The hot chocolate in the large pot has more thermal energy than the hot chocolate in the mug.
The hot chocolate in the large pot has more average kinetic energy than the hot chocolate in the mug.
Explanation:
Thermal energy is defined as the energy posses by an object because of kinetic energy of atoms present in it.
These atoms moves in a great pace or more rapidly when heat is transferred to them hence more the heat more will be the kinetic energy of the material.
In this case, hot chocolate is in large pot and thus has more temperature than the other mug.
Which explains it has more kinetic energy as well as more thermal energy.
A reaction between an acid and a base is called a(n) ________________ reaction. A) hydro B) ionization C) neutralization D) redox
Answer:
It would be a neutralization reaction if i do believe so
Explanation:
A Acid and an Base Neutralize each other you have something too acidic you use a base to neutralize it and same goes for if it is too basic meaning you would use an acid to neutralize it.
Hope it helps =)
Answer: C) neutralization
Explanation:-
B. Ionization is a process in which the most loosely bound electron is removed from an isolated gaseous atom.
[tex]M\rightarrow M^++e^-[/tex]
C. Neutralization is a special type of double replacement reaction in which acid and base combines to form salt and water.
[tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]
D. Redox is a chemical reaction in which oxidation and reduction tales place simultaneously.
[tex]M+N^+\rightarrow M^++N[/tex]
Choose all statements that are true about a GFCI outlet.
A. GFCI outlets are found in dry areas.
B. GFCI outlets prevent house fires.
C. GFCI outlets prevent electrocution if you are touching a wet appliance.
D. GFCI outlets are found in wet areas.
You can pick more than one!
GFCI outlets are found in wet areas is the true statement about a GFCI oulet
Answer: Option D.
Explanation:
GFCI stands for Ground Fault Circuit Interrupter and also named as RCD (Residual Current Device). This is a kind of circuit breaker that cuts off electricity after detecting an imbalance between output and input currents. The switch protects household lines and sockets against overheating and possible fire.
GFCI protects the people and is mostly used in bathrooms or kitchen where electrical equipment is used. Also, it is available where the human body can get into contact with the floor or metal fixings that provide an alternative route to power in the event of a fault. These outlets are available in two versions: the circuit breaker installed in the control panel and receptacle type installed into the electrical box.
A real image is four times as far from a lens as is theobject.
What is the object distance, measured in focal lengths? ____from the lens
Answer:
1.25 focal lengths
Explanation:
The lens equation states that:
[tex]\frac{1}{f}=\frac{1}{p}+\frac{1}{q}[/tex]
where
f is the focal length
p is the object distance
q is the image distance
In this problem, the image is 4 times as far from the lens as is the object: this means that
[tex]q=4p[/tex]
If we substitute this into the lens equation and we rearrange it, we get
[tex]\frac{1}{f}=\frac{1}{p}+\frac{1}{4p}=\frac{4+1}{4p}=\frac{5}{4p}\\p=\frac{5}{4}f=1.25 f[/tex]
so, the object distance measured in focal lengths is
1.25 focal lenghts
The process of bringing a complaint and filing an answer is known as the _____. a. Trials b. Coercions c. Pleadings d. Counterclaim Please select the best answer from the choices provided A B C D
Answer:
pleading
Explanation:
the first step in a lawsuit where parties pass their claims and their defenses. the plaintiff or the one complaining states the issue while the defendant states his answer on the complain and his defense
Final answer:
The process of bringing a complaint and filing an answer in a civil lawsuit is known as the pleadings. Option c.
Explanation:
The process of bringing a complaint and filing an answer is known as the pleadings. In a civil lawsuit, pleadings are the formal documents filed with the court that outline the parties' respective legal positions. The plaintiff initiates this process by filing a complaint, alleging harm or injury, and the defendant responds with an answer, setting forth the grounds for defense. This stage is crucial for setting the case in motion and establishing the issues that will be addressed during the trial or settlement proceedings.
This is the portion of the electromagnetic spectrum that has a frequency just above that of visible light.
i think it’s asking for ultraviolet
Answer:
Ultraviolet Light
Explanation:
A single circular loop with a radius of 35 cm is placed in a uniform external magnetic field with a strength of 0.50 T so that the plane of the coil is perpendicular to the field. The coil is pulled steadily out of the field in 15 s. Find the magnitude of the average induced emf during this interval. Show all work and include units of measure.
Answer:
0.0129 V
Explanation:
The magnitude of the induced emf in the circuit is given by:
[tex]\epsilon = \frac{\Delta \Phi}{\Delta t}[/tex]
where
[tex]\Delta \Phi[/tex] is the change in magnetic flux through the coil
[tex]\Delta t[/tex] is the time interval
To find the change in magnetic flux, we need to find the initial flux and the final flux.
The area of the coil is
[tex]A=\pi r^2 = \pi (0.35 m)^2=0.385 m^2[/tex]
The initial magnetic field is
[tex]B_i = 0.50 T[/tex]
so the initial flux is
[tex]\Phi_i = B_i A = (0.50 T)(0.385 m^2)=0.193 Wb[/tex]
While the final flux is zero, since the coil is completely out of the magnetic field:
[tex]\Phi_f = 0[/tex]
so the magnitude of the change in flux is
[tex]\Delta \Phi = |\Phi_f - \Phi_i|=|0-0.193 Wb|=0.193 Wb[/tex]
While the time interval is
[tex]\Delta t = 15 s[/tex]
so the induced emf is
[tex]\epsilon = \frac{0.193 Wb}{15 s}=0.0129 V[/tex]
During a family trip to Laura's grandmother's house, the family cast traveled a distance of of 8 miles in 24 minutes. During the trip they stopped for two red lights. Which statement correctly describes the motion of the car? And why?
A) The Car Traveled at an acceleration of 0.83 mi/h
B) The Car Traveled at a constant acceleration of 0.83 mi/h
C) The Car Traveled at an average speed of 20 mi/h
D) The Car Traveled at an constant speed of 20 mi/h
The car traveled at an average speed of 20 mi/h. Option C
How to determine the statementThe car will travel at an average speed of 20 mi/h, this is so, because the average speed is calculated as the total distance traveled divided by the total time taken.
In this case, the car traveled a distance of 8 miles in 24 minutes (which is equivalent to 0.4 hours), so the average speed is 8 miles / 0.4 hours = 20 mi/h.
Options A and B mention acceleration, but there is no information provided to calculate acceleration in this scenario.
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What might happen if water molecules did not have a slight negative charge on one end and a slight positive charge on the other?
Answer:
It would not be possible the cohesion among water molecules by the polar covalent bonding.
Well, to understand this in a better way, let's begin by explaining that water is special due to its properties, which makes this fluid useful for many purposes and for the existence of life.
In this sense, one of the main properties of water is cohesion (molecular cohesion), which is the attraction of molecules to others of the same type. So, water molecule ([tex]H_{2}O[/tex]) has 2 hydrogen atoms attached to 1 oxygen atom and can stick to itself through hydrogen bonds.
How is this possible?
By the polar covalent bonding, a process in which electrons are shared unequally between atoms, due to the unequal distribution of electrons between atoms of different elements. In other words: slightly positive and slightly negative charges appear in different parts of the molecule.
Now, it can be said that a water molecule has a negative side (oxygen) and a positive side (hydrogen). This is how the oxygen atom tends to monopolize more electrons and keeps them away from hydrogen. Thanks to this polarity, water molecules can stick together.
If water molecules did not have a slight negative charge on one end and a slight positive charge on the other, several important properties of water would be affected. These properties include the ability of water to form hydrogen bonds, its high boiling point, high surface tension, and its ability to dissolve substances. The polar nature of water molecules is essential for many of the unique properties and functions of water in biological systems and the environment.
Explanation:If water molecules did not have a slight negative charge on one end and a slight positive charge on the other, several important properties of water would be affected. One of these properties is the ability of water molecules to form hydrogen bonds with each other. These hydrogen bonds allow water to have a high boiling point, high surface tension, and the ability to dissolve many substances. Without the polar nature of water molecules, these properties would be significantly altered.
For example, if water molecules were not polar, they would not be able to form hydrogen bonds, which are responsible for water's high boiling point. This means that water would evaporate more easily and at lower temperatures, making it difficult for organisms to survive in aquatic environments. Additionally, water's ability to dissolve other substances, such as salts and nutrients, would be reduced or eliminated altogether.
the farthest major planet from the sun is
The farthest major planet from the sun is Neptune
A photoelectric effect experiment finds a stopping potential of 1.93 V when light of wavelength 200 nm is used to illuminate the cathode.
a.) what metal is the cathode made?
b.) what is the stopping potential if the intensity of light is doubled?
a) zinc
The equation of the photoelectric effect is:
[tex]E=\phi + K[/tex] (1)
where
E is the energy of the incident light
[tex]\phi[/tex] is the work function
[tex]K[/tex] is the maximum kinetic energy of the emitted photoelectrons
Here the wavelength of the incident light is
[tex]\lambda=200 nm = 2\cdot 10^{-7} m[/tex]
so the energy of the light is
[tex]E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{2\cdot 10^{-7} m}=9.95\cdot 10^{-19} J[/tex]
Converting into electronvolts,
[tex]E=\frac{9.95\cdot 10^{-19}}{1.6\cdot 10^{-19} J/eV}=6.22 eV[/tex] (2)
The stopping potential is the potential needed to stop the photoelectrons with maximum kinetic energy: so, the electrical potential energy corresponding to the stopping potential (V=1.93 V) must be equal to the maximum kinetic energy of the photoelectrons,
[tex]U=q V = K[/tex]
and since the charge of the electron is
1 q = 1 e
We have
[tex]K=(1 e)(1.93 V)=1.93 eV[/tex] (3)
Combining (1), (2) and (3), we find the work function of the material:
[tex]\phi = E-K=6.22 eV-1.93 eV=4.29 eV[/tex]
So, the cathode is most likely made of zinc, which has a work function of 4.3 eV.
b) The stopping potential does not change
As we said in part A), the stopping potential is proportional to the maximum kinetic energy of the photoelectrons, K.
The intensity of light is proportional to the number of photons that hit the surface of the metal. However, the energy of these photons does not depend on the intensity, but only on the frequency of the light.
Therefore, the energy of the photons (E) does not change when the intensity of light is doubled. Also, the work function [tex]\phi[/tex] does not change: this means that the maximum kinetic energy of the photoelectrons, K, does not change, and so the stopping potential remains the same.
If the intensity of light is doubled, the stopping potential is still 1.93 V.
What is photoelectric effect ?The term photoelectric effect refers to the fact that electrons are emitted from the surface of a metal when it is irradiated with light of the appropriate frequency.
Now;
Kinetic energy = Energy of photon - work function
Energy of the photon = 6.6 * 10^-34 * 3 * 10^8/200 * 10^-9
= 9.9 * 10^-19 J
For the stopping potential or kinetic energy;
1 ev = 1.6 * 10^-19 J
1.93 eV = 1.93eV * 1.6 * 10^-19 J/1 ev = 3.1 * 10^-19 J
Work function of the metal = 9.9 * 10^-19 J - 3.1 * 10^-19 J
= 6.8 * 10^-19 J or 4.25 eV
The metal is zinc
We know that the stopping potential is independent of the light intensity hence if the intensity of light is doubled, the stopping potential is still 1.93 V.
Learn more about photoelectric effect: https://brainly.com/question/9431503?
Kepler modified Copernicus's model of the universe by proposing that the A. Planets follow a circular orbit around the sun. B. Paths of the planets follow an elliptical orbit around the sun. C. Planets have their own orbits around themselves as they orbit the sun. D. Planets follow an elliptical orbit every leap year.
Answer:
I believe the answer is B, the paths of the planets follow an elliptical orbit around the sun.
Answer:
B. Paths of the planets follow an elliptical orbit around the sun.
Explanation:
As per Copernicus model of the universe he explained that all planets revolves around the sun in circular orbit with sun at the center of the of the path.
Now as per his theory Radius of orbit of all planets are different and the centripetal force provided by the sun for the circular path of the planets
Now as per his theory all planets must have to move with uniform speed around the sun but this was not true as we can see that the speed of all planets are different at different positions.
So here in order to correct his theory Kepler gives his law of planetary motion that all planets revolves around the sun in elliptical orbit with position of sun as one of its focus.
This path verify all the experimental results of planetary motion and hence correct answer will be
B. Paths of the planets follow an elliptical orbit around the sun.