# MCQ Class 9 Science Chapter 11 Work and Energy

Check the below Work and Energy Class 9 MCQ for Science Chapter 11 with Answers available with PDF free download. MCQ Questions for Class 9 Science with Answers were prepared based on the latest syllabus and examination pattern issued by CBSE, NCERT and KVS. Our teachers have provided below Work and Energy Class 9 Science MCQs Questions with answers which will help students to revise and get more marks in exams

## Work and Energy Class 9 Science MCQ Questions with Answers

Refer below for Work and Energy Class 9 MCQ with solutions. Solve MCQ questions and compare them with the answers provided below

Question: At sea level, a nitrogen molecule in air has an average translational kinetic energy of 6.2 × 10–21 J. Its mass is 4.7 × 10–26 kg. If the molecule shoots up straight without resistance,it will rise to a height of
(a) 1.35 km
(b) 13.5 km
(c) 135 km
(d) 1350 km

B

Question: When the momentum of a body is increased by 100%, its K.E. increases by
(a) 100%
(b) 200%
(c) 300%
(d) 400%

C

Question: The power of a water pump is 2 kW. If g = 10 m/s2, the amount of water it can raise in 1 min to a height of 10 m is
(a) 2000 litre
(b) 1000 litre
(c) 100 litre
(d) 1200 litre

D

Question: A rod of mass m and length l is lying on a horizontal table. Work done in making it stand on one end will be
(a) mgl
(b) mgl/2
(c) mgl/4
(d) 2mgl

B

Question: Which of the following graph best represents the kinetic energy (K.E) of a freely falling body and its height h above the ground?

A

Question: In which of the following cases is the potential energy of a spring minimum?
(a) When it is compresse(d)
(b) When it is extende(d)
(c) When it is at its natural length.
(d) When it is at its natural length but is kept
at a height h above the groun(d)

C

Question: Column-I                           Column-II
(P) Kinetic energy                     1. mgh
(Q) Power                                2. 1/2mv2
(R) Potential energy                3. mv
(S) Momentum                         4. W/t
(a) P-2, Q-4, R-1, S-3
(b) P-3, Q-2, R-4, S-1
(c) P-3, Q-4, R-2, S-1
(d) P-1, Q-4, R-3, S-2

A

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

(a) 56 J
(b) 80 J
(c) 90 J
(d) 100 J

A

Question: The speed of a motor bike decreases by 4 times. Its kinetic energy will decrease by
(a) four times
(b) eight times
(c) sixteen times
(d) thirty two times.

C

Question: A man exerts a 80 N force on a load of mass 6 kg along a rough surface. The frictional force acting on the load is 20 N.

Given that the mass moves 5 m horizontally in 30 s, what is the useful power developed by the man?
(a) 10 W
(b) 13 W
(c) 78 W
(d) 300 W

A

Question: Set up the apparatus as shown in figure.

When stone is placed in the pan, trolley moves forwar(d) If you have two stones of masses 10 kg and 5 kg, then in which of the following cases, the block placed in path of trolley suffers maximum displacement?
(Assume that trolley stops after hitting the block.)
(a) When stone of 5 kg is placed in the pan.
(b) When stone of 10 kg is placed in the pan.
(c) When both the stone are placed in the pan.
(d) When the pan is empty.

C

Question: A rocket rises up vertically. What happens to its potential energy?
(a) It increases.
(b) It initially increases then decreases.
(c) It initially decreases then increases.
(d) It increases, till it becomes maximum.

D

Question: There are three paths A, B and C leading to the top of the hill as shown. Assuming that the friction of the ground is negligible, which of the following statements is true?

(a) All three paths require the same amount of energy to reach the top.
(b) Path B requires the least energy to reach the top.
(c) Path C requires most energy to reach the top.
(d) Path B requires more energy than path A to reach the top.

A

Question: A body rolls down on inclined plane, it has
(a) only kinetic energy
(b) only potential energy
(c) both kinetic energy and potential energy
(d) neither kinetic energy nor potential energy

C

Question: A car is accelerating up a slope. What are the changes in its kinetic energy and potential energy as it is moving up the slope?
Kinetic energy Potential energy
(a) decrease decrease
(b) decrease increase
(c) increase increase
(d) increase decrease

C

Question. A girl weighing 400 N climbs a vertical ladder. If the value of g be 10 m s–2, the work done by her after climbing 2 m will be :
(a) 200 J
(b) 800 J
(c) 8000 J
(d) 2000 J

B

Question. A car is accelerated on a levelled road and acquires a velocity 4 times of its initial velocity. During this process, the potential energy of the car :
(a) does not change
(b) becomes twice that of initial potential energy
(c) becomes 4 times that of initial potential energy
(d) becomes 16 times that of initial potential energy

A

Question. Which of the following does not possess the ability to do work not because of motion ?
(a) a sparrow flying in the sky
(b) a sparrow moving slowly on the ground
(c) a sparrow in the nest on a tree
(d) a squirrel going up a tree

C

Question. A car is accelerated on a levelled road and attains a speed of 4 times its initial speed. In this process, the kinetic energy of the car :
(a) does not change
(b) becomes 4 times that of initial kinetic energy
(c) becomes 8 times that of initial kinetic energy
(d) becomes 16 times that of initial kinetic energy

D

Question. An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass 3.5 kg. Both the spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same :
(a) acceleration
(b) momentum
(c) potential energy
(d) kinetic energy

A

Question. In case of negative work, the angle between the force and displacement is :
(a) 0°
(b) 45°
(c) 90°
(d) 180°

D

Question. A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. If the value of g be 10 m/s2, the work done by the girl against the gravitational force will be :
(a) 6000 J
(b) 0.6 J
(c) 0 J
(d) 6 J

C

Question. Water stored in a dam possesses :
(a) no energy
(b) electrical energy
(c) kinetic energy
(d) potential energy

D

Question. The momentum of a bullet of mass 20 g fired from a gun is 10 kg.m/s. The kinetic energy of this bullet in kJ will be :
(a) 5
(b) 1.5
(c) 2.5
(d) 25

C

Question. The work done on an object does not depend on the :
(a) displacement
(b) angle between force and displacement
(c) force applied
(d) initial velocity of the object

D

Question. Each of the following statement describes a force acting. Which force is causing work to be done
(a) the weight of a book at rest on a table
(b) the pull of a moving railway engine on its coaches
(c) the tension in an elastic band wrapped around a parcel
(d) the push of a person’s feet when standing on the floor

B

Question. How much work is done when a body of mass m is raised to a height h above the ground ?

m × g × h

Question A compressed spring.

Potential energy

Question A stretched rubber band.

Potential energy

Question. What happens to the potential energy of a body when its height is doubled ?

Potential energy gets doubled

Question. What is the condition for a force to do work on a body ?

The force should produce motion in the body

Question. What is the work done against gravity when a body is moved horizontally along a frictionless surface ?

Zero

Question A stone kept on roof-top.

Potential energy

Question. By how much will the kinetic energy of a body increase if its speed is doubled ?

Becomes four times

Question. If the speed of a body is halved, what will be the change in its kinetic energy ?

Becomes one-fourth

State whether the following objects possess kinetic energy, potential energy, or both :

Question A man climbing a hill

Both kinetic energy and potential energy

Question A flying aeroplane

Both kinetic energy and potential energy

Question. Two bodies A and B of equal masses are kept at heights of h and 2h respectively. What will be the ratio of their potential energies ?

1 : 2

Question. What is the kinetic energy of a body of mass 1 kg moving with a speed of 2 m/s ?

2 J

Question A bird running on the ground

Only kinetic energy

Question. Which would have a greater effect on the kinetic energy of an object : doubling the mass or doubling the velocity ?

Doubling the velocity

Question. How fast should a man of 50 kg run so that his kinetic energy be 625 J ?

5 m/s

Question A ceiling fan in the off position

Only potential energy

Question A running car.

Kinetic energy

Question Water stored in the reservoir of a dam.

Potential energy

Question A stretched spring lying on the ground.

Only potential energy (rather elastic potential energy)

Question. A load of 100 kg is pulled up by 5 m. Calculate the work done. (g = 9.8 m/s2)

4900 J

Question. State whether the following statement is true or false :
The potential energy of a body of mass 1 kg kept at a height of 1 m is 1 J.

False

Fill in the following blanks with suitable words :

Question The sum of the potential and kinetic energies of a body is called …………… energy.

mechanical

Question Work is measured as a product of ……………….. and ……………..

force ; distance

Question 1 joule is the work done when a force of one ………….. moves an object through a distance of one………… in the direction of …………………

newton ; metre ; force

Question The work done on a body moving in a circular path is ……………..