Free Printable work and energy

1.

When a body falls freely towards the earth, then its total energy

a)

(a) increases

b)

(b) decreases

c)

(c) remains constant

d)

(d) first increases and then decreases

2.

In case of negative work the angle between the force and displacement is

a)

(a) $0\degree$

b)

(b) $45\degree$

c)

(c) $90\degree$

d)

(d ) $180\degree$

3.

An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same

a)

(a) acceleration

b)

(b) momenta

c)

(c) potential energy

d)

(d) kinetic energy

4.

Which one of the following is not the unit of energy?

a)

(a) joule

b)

(b) newton metre

c)

(c) kilowatt

d)

(d) kilowatt hour

5.

The work done on an object does not depend upon the

a)

(a) displacement

b)

(b) force applied

c)

(c) angle between force and displacement

d)

(d) initial velocity of the object

6.

Water stored in a dam possesses

a)

(a) no energy

b)

(b) electrical energy

c)

(c) kinetic energy

d)

(d) potential energy

7.

A body is falling from a height h. After it has fallen a height $\frac{h}{2}$ , it will possess

a)

(a) only potential energy

b)

(b) only kinetic energy

c)

(c) half potential and half kinetic energy

d)

(d) more kinetic and less potential energy

8.

The number of joules contained in 1kWh is

a)

$36\times10^{6\ ^{ }}J$

b)

$3.6\times10^{7^{ }}J$

c)

$3.6\times10^{6^{ }}J$

d)

$3.7\times10^{7^{ }}J$

9.

Two army persons A and B each of weight of 500N climb up a rope through a height of 10m.

A takes 20s while B takes 40s to achieve this task. what is ratio of the power of person A and B?

a)

1:2

b)

1:4

c)

2:1

d)

14:1

10.

If speed of a car becomes 2 times, its kinetic energy becomes

a)

4 times

b)

8 times

c)

16 times

d)

12 times

11.

Mechanical energy of a body includes

a)

Kinetic energy only

b)

Potential energy only

c)

kinetic energy and potential energy

d)

None of these

12.

Commercial unit of energy is

a)

Joule

b)

kWh

c)

Watt

d)

Newton

13.

When a coil spring is compressed, the work is done on the spring. the elastic potential energy

a)

Increases

b)

Decreases

c)

Disappears

d)

Remain unchanged

14.

In tug of war work done by loosing team is :

a)

Zero

b)

Positive

c)

Negative

d)

None of these

15.

Work done upon a body is :

a)

A vector quantity

b)

A scalar quantity

c)

Both A and B are correct

d)

None of these

16.

A particle of mass m is at rest is acted upon by a force F for a time t. Its kinetic energy after an interval of t is :

a)

F²t²/m

b)

F²t²/2m

c)

F²t²/3m

d)

Ft/2m

17.

A device which converts the electrical energy into mechanical energy is called :

a)

Dynamo

b)

Electromagnet

c)

Electric motor

d)

Generator

18.

In a simple pendulum mass of bob is 100 g and effective length is L. Work done on the pendulum in one complete oscillation by gravitational force is:

a)

1/4 x mgL

b)

1/2 x mgL

c)

Zero

d)

mgL

19.

Energy possessed by a body by virtue of its motion is called :

a)

Potential energy

b)

Kinetic energy

c)

Gravitational energy

d)

None

20.

A boy pushes a book kept on a table by applying a force of 4.5 N. find the work done by the force, if book is displaced through 30 cm along the direction of push

a)

1.10 J

b)

1.25 J

c)

1.35 J

d)

None

21.

The kinetic energy of an object is K. If its velocity is doubled then its kinetic energy will be :

a)

K

b)

2K

c)

K/2

d)

4K

22.

Formula of work

a)

Fs

b)

ma

c)

J

d)

g

23.

Total Energy E_T =

a)

Ep + Ek

b)

Mass / Area

c)

w/t

d)

none of these

24.

Si unit of power

a)

Watt

b)

ma

c)

pa

d)

1J/s

25.

1KW = ?

a)

1000w

b)

100w

c)

10000w

d)

none

26.

Define potential energy.

a)

Energy due to temperature

b)

Energy due to color

c)

Energy due to position or state

d)

Energy due to motion

27.

A force of 20 N is applied to move an object 5 meters. Calculate the work done.

a)

100 J

b)

50 J

c)

200 J

d)

10 J

28.

What is the kinetic energy of an object with a mass of 8 kg and a velocity of 6 m/s?

a)

72 J

b)

100 J

c)

144 J

d)

48 J

29.

Calculate the potential energy of an object with a mass of 3 kg and a height of 8 meters.

a)

123.8 joules

b)

235.2 joules

c)

17.2 joules

d)

56.4 joules

30.

When a body falls freely towards the earth, then its total energy

a)

(a) increases

b)

(b) decreases

c)

(c) remains constant

d)

(d) first increases and then decreases

31.

In which of the following instances, work is not done

a)

(a) A man standing with a suitcase in his hand

b)

(b) A sail boat moving in the direction of wind

c)

(c ) A man swimming in a pond

d)

(d) A windmill lifting water from a well

32.

The sun is continuously releasing heat energy. This is due to the transformation of -------energy

a)

(a) mechanical to heat

b)

(b) electrical to heat

c)

(c ) chemical to heat

d)

(d) nuclear to heat

33.

How much work is done on the lawnmower by the person if he exerts a constant force of 70 N at an angle 180º below the horizontal and pulls the mower 25m on level ground?

a)

(a) 1750 J

b)

(b) -1750 J

c)

(c) -175 J

d)

(d) 175 J

work and energy

Total questions: 33

Worksheet time: 30mins

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