Potential Energy

Q. Give examples of kinetic energy and potential energy

Q.

What is the ability to do work called?

Q.

Calculate the potential energy of a body of mass 5 kg at height of 2 m from the ground

Q.

When force and displacement are in perpendicular directions, the work is _______ .

Q. Differences between kinetic energy and potential energy?

Q. What type of energy is stored in the spring of a watch?

Q.

Write a short note on gravitational potential energy.

Q.

What is Joule?

Q.

During a tug of war, team A pulls on team B by applying a force of $1100N$ on the rope between them. How much work does team A do if they pull team B towards them by a distance of $2m$.

Q.

A force of $20N$ acts on a body and displaces it $2m$ along the direction of the force. Then the work done by the force is:

Q.

List the disadvantages of thermal energy.

Q.

When is work done equal to kinetic energy and when is it equal to potential energy?

Q. A boy of mass 50kg runs up a staircase of 45 steps in one second. If height of each step is 15cm, find power generated by him. (g=10 m/s²)

Q.

When an object is thrown up, its potential energy ______ and its kinetic energy ______ till it reaches the highest point.

Q.

What kind of energy is possessed by the following ?

(a) A stone kept on roof-top

(b) A running car.

(c) Water stored in the reservoir of a dam.

(d) A compressed spring.

(e) A stretched rubber band.

Q. A stretched catapult possesses energy.

1. potential
2. kinetic
3. electrical

Q.

Whenever there is no change in kinetic energy, there will always be a change in potential energy.

1. True

2. False

Q.

A heavy stone falls :

1. faster than a light stone

2. slower than a light stone

3. with same acceleration as light stone

4. none of these

Q.

The potential energy of a boy is maximum when he is:

1. standing

2. Sleeping on the ground

3. Sitting on the ground

4. Sitting on chair

Q. A ball of mass $50g$ is thrown vertically upwards with an initial velocity $20m{s}^{-1}$. Calculate the maximum height reached, if air friction is neglected. Take $g=10m{s}^{-2}$.

1. 20 m
2. 30 m
3. 40 m
4. 10 m

Q.

A body at rest may have

1. energy

2. momentum

3. speed

4. velocity

Q.

A hammer falls freely from the height of 2 m. Calculate the velocity (in m/sec) of the hammer when it just touches the ground. $(takeg=10m/se{c}^2)$

Q.

A force of $7N$ acts on an object. The displacement is, say $8m$, in the direction of the force. Let us take it that the force acts on the object through the displacement. What is the work done in this case?

Q.

When you lift a box from the floor and put it on almirah, potential energy of the box increases but there is no change in its kinetic energy. If there is no change in its kinetic energy, then how does the potential energy increase?

Q. An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down. [3 MARKS]

Q. What happens to the potential energy of an object, if its mass is doubled and the height to which it is lifted is halved of its initial state?

1. Becomes half.
2. Becomes quadruple.
3. Remains same.
4. Becomes double.

Q. Determine The amount of potential energy of a 5 Newton book that is moved from the ground to 3 different shelves on a book case. The height of each shelves is 1 m 1.5 m and 2 m from the ground

Q.

If you apply 1 J of energy to lift a book of 0.5 kg, how high will it rise? Consider that gravity = 10 $\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s^2$}\right.$.

Q.

A man lifts a luggage of $10kg$ from the ground and puts it on his head $1.7m$ above the ground. Calculate work done by man on the luggage. Take acceleration due to gravity $g=10m/s^2$

1. 180 J

2. 170 J

3. 200 J

4. 150 J

Q. 500 litres of water is raised from the first floor of a house at height 4 m to its third floor at height 12 m. If density of water is $1kg{l}^{-1}$ then the change in potential energy is (take $g=10m{s}^{-2}$):

1. increase in potential energy is $4\times {10}^{4}J$
2. decrease in potential energy is $4\times {10}^{4}J$
3. increase in potential energy is $2\times {10}^{4}J$
4. decrease in potential energy is $4\times {10}^{4}J$