10 QA on work power energy

10 QA on work power energy | Learn Physics

10 Question-Answer on work power energy

1. If two protons are brought near one another, the potential energy of the system will:

(a) Increase

(b) Decrease

(d) Equal to the kinetic energy

Ans: (a)

2. A water pump driven by petrol raises water at a rate of 0.5 m³/min. from a depth of 30 m. If the pump is 70% efficient the power developed by the engine is:

(a) 1750 W

(b) 2450 W

(d) 7000 W

Ans: ( c)

3. The energy required to accelerate a car from 10 m/s to 20 m/s is n times the energy required to accelerate the same from rest to 10 m/s, where n is :

(a) 1

(b) 4

(d) 3

Ans: ( d)

4. A man is riding on a cycle with velocity 7.2 km/h up a hill having a slope 1 in 20. Total mass of the man and cycle is 100 kg. The power of a man is:

(a) 98 W

(b) 49 W

(d) 147 W

Ans : (a)

5. A body is moving under the action of a force. Suddenly, force is increased to such an extent that its kinetic energy is increased by 100%. The momentum increases by:

(a) 100%

(b) 60%

(d) 20%

Ans: (c )

6. The slope of potential energy versus position graph represents

(a) Force

(b) Work

(d) Momentum

Ans: ( a)

7. A boy – pushes a toy box 2.0 m along the floor by means of a force of 10 N directed downward at an angle 60˚ to the horizontal The work done by the boy is:

(a) 6 J

(b) 8 J

(d) 12 J.

Ans: (c)

8. Tape recorder records the sound in the form of :

(a) Electrical energy

(b) Magnetic field on the tape

(d) Sound wave held on the tape

Ans: (b)

9. What is the shape of the graph between the speed and kinetic energy of a body?

(a) Straight line

(b) Hyperbola

(d) Exponential

Ans: (c )

10. The negative of the work done by the conservative internal force on a system equals the change in:

(a) Potential energy

(b) Kinetic energy

(d) None of these

Ans: (a)

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