Which of the following materials offer the least electrical resistance? Pure water, wood, salt water, glass

The option stating that the observer must be placed within the focal length is false or not a necessary condition for magnification.

Explanation:

Lens are used for magnification provided the nature of the lens is known and by positioning the object at correct position. So the object should be placed in the focal point of the lens for perfect magnification, it can also be kept within the focal point or focal length. But the object should not be kept beyond the focal length of the lens.

So among the given options, the object and image should be on the same side of the lens for magnification is true. Then the nature of lens should be converging for magnification is also true. And the most important point that the object should be placed within the focal length of the lens is the most mandatory for obtaining magnification. So the option stating that the observer must be placed within the focal length is false or not a necessary condition for magnification.

The force on the book that has a mass of 50 grams and an acceleration of 5 m/s² is 250N.

The force of an object can be calculated by multiplying the mass by its acceleration as follows:

Force = mass × acceleration

According to this question, a book has a mass of 50 grams and an acceleration of 5 m/s². The force is as follows:

Force = 50 × 5

Force = 250N

Therefore, the force on the book that has a mass of 50 grams and an acceleration of 5 m/s² is 250N.

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The correct force on the book is 2.5 N.

To find the force on the book, we can use Newton's second law of motion, which states that force is equal to mass times acceleration (F = m × a).

Given:

- The mass of the book (m) is 50 grams. To convert grams to kilograms (since the standard unit of mass in the SI system is kilograms), we divide by 1000. Thus, m = 50 / 1000 kg = 0.05 kg.

- The acceleration (a) of the book is 5 m/s².

Using Newton's second law, we calculate the force (F) as follows:

F = m × a

F = 0.05 kg × 5 m/s²

F = 0.25 kg × m/s²

Since 1 Newton is equal to 1 kgm/s², the force on the book is 0.25 Newtons, or 2.5 N.

Therefore, the correct answer is 2.5 N, which is not listed in the given options. It seems there was a typo in the provided options, as the correct calculation does not result in any of the listed forces. The closest option to the correct answer is 20 N, but it is still incorrect. The correct force is 2.5 N.

A paper clip is an example of a magnetic material that can be temporarily magnetized by rubbing it with a permanent magnet, causing it to attract other ferromagnetic objects like another paper clip.

A paper clip is an example of a magnetic material. Magnetic materials are materials that can be magnetized and are attracted to magnets. Some commonly known magnetic materials include iron, nickel, and cobalt. In this case, the paper clip can be attracted to a magnet because it contains iron, which is a magnetic material.

A paper clip is an example of a magnetic material. When you rub a permanent magnet along a paper clip, the paper clip becomes temporarily magnetized due to the alignment of the magnetic domains within the material. This temporary magnetization allows the paper clip to exhibit magnetic properties, such as attracting other ferromagnetic objects. If you place this magnetized paper clip near another paper clip, the untouched paper clip will experience an attractive force, as seen in classroom experiments. Ferromagnetic materials like iron, which paper clips are commonly made of, can be magnetized and therefore are strongly attracted to magnets, unlike insulators or temporary electromagnets that require a current to become magnetized.

Answer:

Explanation:

Heat transfer by conduction only happens by direct contact of the molecules or atoms of a substance: in a solid, particles cannot travel but only vibrate; the heat conduction happens because the vibration of a particle causes adjacent particles to vibrate.

Also, in that system heat transfer by convection would not happen, since convection requires that the particles travel to transfer the heat.

Only heat transfer by radiation can happen when there are no particles, since infrared radiation travels through the empty space.

Answer:

Seismic waves cause Earthquakes by shaking the ground aggressively and dangerously. These waves are usually calculated on a seismograph to calculate how hard the earthquake hit that area. A transform Boundary creates the tension when the tectonic plates gets stuck. It stays stuck for a long period of time. Then, at one point, the tectonic plates become unstuck which releases the tension into waves which are called seismic waves. Hope I answered you question.

Sound waves don't cause earthquakes.

When parts of the Earth shake and quake and rub against each other, THAT's an earthquake.

THEN, whenever anything is shaking, THAT makes sound waves.

The amount of heat needed to melt 35 g of ice will be equal to 2,800 calories and in kilojoule is 11.7152 KJ.

Heat is energy that is transmitted from one object to another when temperatures are varied. When two bodies of various temperatures are brought together, energy is exchanged, or heat flows, from the hotter body to the colder. The result of this transfer of energy is typically, but not always, a warming of the colder body and a reduction in the temperature of the hotter body.

By migrating from one physical state (or phase) to the other, such as melting from a solid to a liquid, sublimation from the solid to a vapor, boiling from a fluid to a vapor, or shifting through one solid form to the other, a substance can absorb heat while increasing in temperature.

The latent heat of ice = 80cal/g.

So, the amount of heat required

= 35× 80cal

= 2,800 cal. Or,

2800 × 0.004184 = 11.7152 KJ.

Therefore, the amount of heat needed to melt the ice is 11.7152 KJ.

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Answer:

B for Edgunity

Explanation:

Answer:

same force, but in the opposite direction

Explanation:

As we know that the electrostatic force between two charges is given by Coulomb's law of electrostatics

It is given by

[tex]F = \frac{kq_1q_2}{r^2}[/tex]

so here we can say that the initial force between the given charges is

[tex]F = \frac{(9\times 10^9)(3\mu C)(-5\mu C)}{(0.002)^2}[/tex]

nowwe replace the charge  -5 uC to another charge which is + 5 uC

so here new force will be

[tex]F = \frac{(9\times 10^9)(3\mu C)(5\mu C)}{(0.002)^2}[/tex]

now from above equation we can say that magnitude of the force will be same only the nature of the force will change as initially two opposite charges were there so they will attract each other while in new position there are two similar charges so they will repel each other

so correct answer will be

same force, but in the opposite direction

Answer:

A. same force, but in the opposite direction

Explanation:

I got u bro,

e2021 btw

Explanation:

The work done to lift the bag of weight mg through height 2.5 m is 400 J

The work done can be found by relation  W = mg x h

Thus mg = [tex]\frac{W}{h}[/tex] = [tex]\frac{400}{2.5}[/tex] =  160 N

Therefore the man have to apply the force of 160 N

Answer:160newtons

Explanation:

Work=400J

Distance=2.5m

Time=2 seconds

Force=?

Force=work/distance

Force=400/2.5

Force=160

Force=160 newtons

Answer: 64.91 m/s

Explanation:

This situation is related to free fall, since we are told the piece of glass "dropped".

Now, since this can be considered a one-dimension problem, we can use the following equation:

[tex]V^{2}=V_{o}^{2}+2gd[/tex]

Where:

[tex]V[/tex] is the final velocity of the glass

[tex]V_{o}=0 m/s[/tex] is the initial velocity of the glass

[tex]g=9.8 m/s^{2}[/tex] is the acceleration due gravity

[tex]d=215 m[/tex] is the distance from where the glass fell

Isolating [tex]V[/tex]:

[tex]V=\sqrt{V_{o}^{2}+2gd}[/tex]

[tex]V=\sqrt{2(9.8 m/s^{2})(215 m)}[/tex]

[tex]V=64.91 m/s[/tex] This is the final velocity of the glass

Answer:

Kinetic energy will increase from 0 J to 12 J and the potential energy will decrease from 12 J to 0 J.

Explanation:

-As the bob swings downwards it loses height. So its gravitational potential energy (GPE) decreases.

-The subsequent work done on the pendulum by the gravitational force increases its kinetic energy.

-At all points, by Law of Conservation of Mechanical Energy, during the swing the total ptential energy  plus kinetic energy is constant.

Answer:

Explanation:

give that person brainlist

The power of a machine depend on two factors are work and time.

Option C

Explanation:

In science, power defined as the amount of work done in a unit time. i.e. delivering work in a rate of time or energy supply, expressed in input of work or transmitted energy divided by the time interval (t) or W/t.

Example: Some work can be done in the long run with a low-power engine or in a short time with a motor with high performance. The equation for power can be given as

              [tex]Power\ (in\ watts) =\frac{\text { work (joules) }}{\text { time (seconds) }}[/tex]

              [tex]P=\frac{W}{t}[/tex]

Answer:

Diffraction of sound wavelengths.

Explanation:

[tex]Diffraction[/tex]-A wave is able to bend around a corner due to the effects of diffraction. sound aves are capable of bending around corners in the same magnitude as it's wavelength making it possible to hear sounds around corners.

Yes, Kinetic Energy is a scalar quantity because the direction is not needed.  A scalar quantity is one dimensional measurement.

Explanation:

The kinetic energy is a scalar quantity as it requires only magnitude for description.

Explanation:

Scalar quantity refers to the quantity that has a single dimension. It is not dependent on the direction and has magnitude only, like Temperature and Mass.

Kinetic energy is possessed when the object is set in motion. Any object whether it is moving straight or spinning possess kinetic energy. It depends on two variables, namely, mass and velocity or speed of the object.

Kinetic Energy:  K.E. = [tex]\frac{1}{2}[/tex] × m × v²

The metric unit to measure Kinetic energy is Joule (J).  

There are three plate boundaries: Constructive, Destructive and transform plate boundary. At constructive plate boundary mountains form, at destructive plate boundaries earthquake and volcanism occurs and at transform boundary faults occur.

Explanation:

Plates are solid and rigid mass. It mainly floats over asthenosphere which is a part of upper mantle. There are seven major plates and twenty minor plates. The zone between two plates are known as plate boundary and the edge of a plate is known as plate margin.

There are three plate boundaries: Conservative, destructive and transform plate boundary. Where two plates collide with each other known as destructive plate boundary and where two plates move in opposite direction from each other known as constructive plate boundary. Where two plates slide each other called transform fault.

Answer:

Volcanoes are one kind of feature that forms along convergent plate boundaries, where two tectonic plates collide and one moves beneath the other.

Explanation:

Answer:

1.50 h

Explanation:

For an object moving in uniform motion (= moving at  cosntant velocity), the relationship between speed, distance and time is given by:

[tex]v=\frac{d}{t}[/tex]

where:

v is the speed of the object

d is the distance covered

t is the time taken to cover the distance

For this problem, we have:

d = 18 miles is the distance covered by David

[tex]v=12 mi/h[/tex] is David's speed

Therefore by re-arranging the equation, we can find the time taken by David to cover that distance:

[tex]t=\frac{d}{v}=\frac{18}{12}=1.5 h[/tex]

Answer:

The answer is B

Explanation:

I just took it on USATESTPREP

Filtration is the best method to separate sand from water because sand is insoluble, filter paper can trap sand particles, and crystallization does not collect water.

The best method to separate sand from water in this scenario is Filtration. Filtration is a process that uses a porous material, such as filter paper, to separate solid particles from a liquid. This method is effective because:

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Answer:

It depends on the frequency and amplitude of the wave itself. Or a more simple way would be if you have a diagram or a picture take a ruler and measure in cm to get the wavelength. Hope this helped!

Explanation:

Answer:

It decreases the frequency by 33.33%

Explanation:

The frequency of a wave is given by the division between its velocity and its wavelength:

f = v/L, where f is the frequency in hertz, v is the velocity in m/s, and L is the wavelength in meter

If we increase the wavelength by 50 percent, we have that L' = 1.5*L (L' is the new wavelength)

Keeping the same velocity, we have the new frequency (f') as:

f' = v/L' = v/1.5*L = (1/1.5)*v/L = 0.6667*f

The new frequency is 66.67% of the old frequency, that is, the old frequency decreased 33.33%.

So, increasing the wavelength by 50% decreases the frequency by 33.33% or 1/3

Increasing the wavelength by 50 percent reduces the frequency of a wave by half.

Increasing the wavelength by 50 percent affects the frequency of a wave on a rope by reducing the frequency by half. The wavelength and frequency of a wave are inversely proportional, meaning that as the wavelength increases, the frequency decreases and vice versa. This relationship is represented by the equation: frequency = speed / wavelength.

For example, let's say the original wavelength of a wave on a rope is 2 meters and the frequency is 10 Hz. If we increase the wavelength by 50 percent, it becomes 3 meters. Using the equation, the new frequency would be: frequency = speed / 3 meters = 10 Hz / 3 = 3.33 Hz.

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Answer:

The planet will experience a force of [tex]1.72*10^{23}N[/tex]

Explanation:

The force of gravity [tex]F[/tex] experienced by the planet is of mass [tex]m[/tex] at a distance [tex]R[/tex] from a star of mass [tex]M[/tex] is given by

[tex]F = G\dfrac{mM}{R^2},[/tex]

where [tex]G= 6.7*10^{-11}Nm^2 /kg^2[/tex] is the gravitational constant.

The mass of the star is two times that of the sun:

[tex]M = 2*M_{sun} = 2*(2* 10^{30}kg) = 4*10^{30}kg[/tex],

the mass [tex]m[/tex] of the planet is

[tex]m = 5.4*10^{27}kg[/tex],

the distance [tex]R[/tex] of the planet form the star is

[tex]R =2.897*10^9km = 2.897*10^{12} m[/tex];

therefore, the force of gravity on the planet will be

[tex]F = (6.7*10^{-11})\dfrac{(5.4*10^{27}kg)(4*10^{30}kg)}{(2.897*10^{12}m)^2}[/tex]

[tex]\boxed{F = 1.72*10^{23}N }[/tex]

which is the force that the planet will experience.

Answer:

In a transverse wave the particles of the medium move perpendicular to the wave's direction of travel.

In a longitudinal wave, the particles of the medium move parallel to the wave's direction of travel.

Answer:

Electric energy moves through the wire to the lamp's bulb. In the bulb's filament, electric energy transforms into thermal energy and light energy.

Explanation:

Answer:

[tex]u = 2.5 \ m/s[/tex]

Explanation:

Given data:

Height, [tex]h = 210 \ m[/tex]

Time, [tex]t = 6.3 \ s[/tex]

Let the initial velocity of the object be u.

From the kinematic equation,

[tex]h = ut + \frac{1}{2}gt^{2}[/tex]

[tex]210 = u \times 6.3 + 0.5 \times 9.80 \times (6.3)^{2}[/tex]

[tex]\Rightarrow \ u = 2.46 \ m/s[/tex]

[tex]u = 2.5 \ m/s[/tex] (rounding to tenth place)

Final answer:

The object's initial velocity was calculated to be 62 m/s after falling 210 m in 6.3 s.

Explanation:

The initial velocity of the object can be calculated using the formula:

v = u + gt

where:

v is the final velocity (0 m/s as the object stops), u is the initial velocity, g is the acceleration due to gravity (-9.8 m/s²), and t is the time taken (6.3 s).

Plugging in the values:

0 = u - 9.8*6.3

u = 9.8*6.3

u = 61.74 m/s

Rounded to the correct significant digits:

u = 62 m/s

Answer:

Air resistance: 68.6 N

Explanation:

For the skydiver falling down, there are two forces acting on him:

- The force of gravity, of magnitude

[tex]W=mg[/tex]

where

m = 7.0 kg is the mass of the skydiver

[tex]g=9.8 m/s^2[/tex] is the acceleration of gravity

This force acts in the downward direction

- The air resistance, R, in the upward direction

So the net force on the skydiver is:

[tex]\sum F=mg-R[/tex]

According to Newton's second law of motion, the net force is also equal to mass times acceleration:

[tex]\sum F=ma[/tex]

However, in this problem the skydiver is falling at constant velocity, so his acceleration is zero:

[tex]a=0[/tex]

Therefore, the net force is zero:

[tex]\sum F=0[/tex]

And so we can find the magnitude of the air resistance, which is equal to the weigth of the skydiver:

[tex]mg-R=0\\R=mg=(7.0)(9.8)=68.6 N[/tex]

This question involves the physics concept of terminal velocity. It's the constant speed a skydiver descends when the force of gravity equals the upward force of air resistance.

The subject of this question involves a concept in physics known as terminal velocity. When a skydiver jumps out of a plane, gravity pulls them downwards, while air resistance pushes upwards. As the skydiver falls faster, air resistance increases until it is equal to the pull of gravity. At this point, the skydiver no longer accelerates and falls at a constant velocity. This is the terminal velocity. In this particular case, the fact that the 7.0kg skydiver is descending at a constant velocity tells us that he has reached his terminal velocity.

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Answer:117.6joules

Explanation:

Mass(m)=2kg

Height(h)=6m

Acceleration due to gravity(g)=9.8m/s^2

Potential energy(PE)=?

PE=m x g x h

PE=2 x 9.8 x 6

PE=117.6joules

Answer:

3.2m

Explanation:

Given parameters:

Frequency of the FM radio = 9.23 x 10⁷Hz

Velocity of the waves = 3  x 10⁸m/s

Unknown:

Wavelength of the wave = ?

Solution:

To solve for the wavelength of the wave, we need the velocity equation;

       Velocity = frequency x wavelength.

Radio waves are all electromagnetic radiations produced by both electrical and magnetic fields perpendicularly oriented to one another.

 Since the unknown is wavelength, we solve for it:

    3  x 10⁸  = 9.23 x 10⁷ x wavelength

          wavelength = [tex]\frac{ 3 x 10^{8} }{9.23 x 10^{7} }[/tex]

        wavelength = 3.2m

Answer:

3.25

Explanation:

on edge :)

Answer:

The detailed calculations are shown below;

Explanation:

a)The maximum acceleration of the particle:

  It is seen that the maximum change in velocity is at the time between 8s to 10s.

              Maximum acceleration: [tex]\frac{V}{t}[/tex]

                                                    = [tex]\frac{20}{2}[/tex]

                                                    = 10 m/[tex]s^{2}[/tex]

b) The deceleration of the particle

          The velocity of particle is decreased after 10s so,

                     deceleration = - [tex]\frac{40}{6}[/tex]

                                           = - 6.67 m/[tex]s^{2}[/tex]

c)The total distance traveled by the particle = Area under the curve

                               = [tex]\frac{1}{2}[/tex]* 4*20 + 4*20 +  [tex]\frac{1}{2}[/tex]* 2*20+ 2*20+ [tex]\frac{1}{2}[/tex]* 40*16

                                                       = 290 m

d)The average velocity of the particle = [tex]\frac{Area under the curve}{Total time}[/tex]

                                                               = [tex]\frac{290}{16}[/tex]

                                                               = 18.12 m/s

The weight of the needle = 0.007 N

Explanation:

Step 1 :

Given,

Length of the needle = 5 cm = 5 × [tex]10^{(-2)}[/tex] m

Surface tension of the water =0.07 N/m​

We need to find the weight of the needle.

Step 2 :

We have

weight = (surface tension) × 2l

where l is the length of the object

The total contact length between the needle and water is 2 times the length of the needle.

Therefore

weight of the needle = 0.07 × 2 × 5 × [tex]10^{(-2)}[/tex]  = 0.007 N

Step 3 :

Answer :

The weight of the needle = 0.007 N        

The weight of the needle is 0.0035N

In order for a needle to rest on the surface of water without wetting, the force due to the weight of the needle must be balanced by the surface tension of the water. The weight of the needle can be calculated using the formula:

Weight = Mass x Acceleration due to gravity

Given that the length of the needle is 5cm and the surface tension of the water is 0.07N/m, we can find the weight of the needle by converting the length into meters and multiplying by the surface tension.

Weight of the needle = Length x Surface tension = 0.05m x 0.07N/m = 0.0035N.

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Answer:

2000000j

Explanation:

m*g*h

2000*100*10

=2000000

Answer:

#See solution for details.

Explanation:

-Friction is the force exerted on an object moving against it.

-Friction acts in the opposite direction to the object's motion.

-As such, friction reduces the motion of an object. The object is usually slowed down. The resultant motion of the object is less than the force applied on it.