CLASS: IX NCERT (CBSE)

PHYSICS

Work and Energy

Question (1): Work done = Force x _______

1. distance

2. acceleration

3. velocity

4. speed

Ans: 1

Question (2): 1 joule = 1 _______

1. N m2

2.

3. N m

4. N2 m2

Ans: 3

Question (3): Which form of energy does the flowing water possess?

1. gravitational energy

2. potential energy

3. electrical energy

4. kinetic energy

Ans: 4

Question (4): A body of mass 2 kg is dropped from a height of 1m. Its kinetic energy as it touches the ground is _______

1. 19.6 N

2. 19.6 J

3. 19.6 kg

4. 19.6 m

Ans: 2

Question (5): The unit of power is _______

1. watt per second

2. joule

3. kilojoule

4. joule per second

Ans: 4

Question (6): 3730 watts = ______h.p.

1. 5

2. 2

3. 746

4. 6

Ans: 1

Question (7): A coolie carries a load of 500 N to a distance of 100 m. The work done by him is

1. 5 N

2. 50,000 Nm

3. 0

4. 1/5 N

Ans: 3

Question (8): The P.E. of a body at a certain height is 200 J. The kinetic energy possessed by it when it just touches the surface of the earth is

1. > P.E.

2. < P.E.

3. = P.E.

4. cannot be known

Ans: 1

Question (9): Power is a measure of the _______

1. rate of change of momentum

2. force which produces motion

3. change of energy

4. rate of change of energy

Ans: 4

Question (10): Two objects of masses 1 x 10-3 kg and 4 x 10-3 kg have equal momentum. What is the ratio of their kinetic energies?

1. 4:1

2. 2:1

3. 16:1

4.

Ans: 1

Question (11): A 40 newton object is released from a height of 10 m. Just before it hits the ground, its kinetic energy, in joules is _______

1. 400

2. 3920

3. 2800

4. 4000

Ans: 1

Question (12): If the speed of an object is doubled then its kinetic energy is _______

1. doubled

2. quadrupled

3. halved

4. tripled

Ans: 2

Question (13): 1.5 kW = ______ watts

1. 1500

2. 150

3. 15000

4. 15

Ans: 1

Question (14): A man of mass 50 kg jumps to a height of 1 m. His potential energy at the highest point is (g = 10 m/s2)

1. 50 J

2. 60 J

3. 500 J

4. 600 J

Ans: 3

Question (15): The type of energy possessed by a simple pendulum, when it is at the mean position is

1. kinetic energy

2. potential energy

3. potential energy + kinetic energy

4. sound energy

Ans: 1

Question (16): An iron sphere of mass 30 kg has the same diameter as an aluminium sphere whose mass is 10.5 kg. The spheres are dropped simultaneously from a cliff. When they are 10 m from the ground, they have the same _______.

1. acceleration

2. momentum

3. potential energy

4. kinetic energy

Ans: 1

Question (17): A 1 kg mass has a kinetic energy of 1 joule when its speed is

1. 0.45 m/s

2. 1 m/s

3. 1.4 m/s

4. 4.4 m/s

Ans: 3

Question (18): If air resistance is negligible, the sum total of potential and kinetic energies of a freely falling body _______

1. increases

2. decreases

3. becomes zero

4. remains the same

Ans: 4

Question (19): Name the physical quantity which is equal to the product of force and velocity.

1. work

2. energy

3. power

4. acceleration

Ans: 3

Question (20): An object of mass 1 kg has potential energy of 1 joule relative to the ground when it is at a height of _______.

1. 0.102 m

2. 1 m

3. 9.8 m

4. 32 m

Ans: 1