**Q1. Calculate the power developed when the force of 10 N is exerted on a body moving with a velocity of 3.65 m/s. **

- 0.365 W
- 36.5 W
- 365 W
- 3.65 W

**Answer :- (2)**

**Q2. If a body in rest breaks up into two pieces of equal masses, then, the parts will**

- Move in the same direction.
- Move in opposite directions with equal speeds
- Remain at rest.
- Move in opposite directions with unequal speeds.

**Answer :- (2)**

**Q3. An electric motor creates a tension of 4500 N in a hoisting cable and reels it in at the rate of 2 m/s. What is the power of the electric motor?**

- 15 kW
- 9 kW
- 225 W
- 900 W

**Answer :- (2)**

**Q4. Work done in motion of the body over a closed loop for conservative forces is**

- zero
- non-zero
- infintesimal
- infinity

**Answer :- (1)**

**Q5. How should the force applied on a body be varied with velocity to keep the power of force constant?**

- Force should be directly proportional to the velocity of the body
- Force should be inversely proportional to the square root of the velocity of the body
- Force should not be varied. It should remain constant with the velocity
- Force should be inversely proportional to the velocity of the body

**Answer :- (4)**

**Q6. A shell, in its flight explodes into five unequal parts. Which of the following is conserved?**

- Momentum
- Kinetic energy
- Potential energy
- Both potential energy and kinetic energy.

**Answer :- (1)**

**Q7. A person A pushes a body of 5 kg placed on a rough surface of co-efficient of friction 0.3 by a distance of 4 m in 15 seconds. Another person B pushes the body of 7 kg on same surface by a distance of 3 m in the same time. Who has more energy and power?**

- A
- B
- Both A and B have developed equal power but B has more energy
- Both A and B have developed equal power but A has more energy

**Answer :- (2)**

**Q8. What is the CGS unit of power?**

- 1 erg / hr
- 1 dyne / sec
- 1 erg / sec
- 1 dyne / hr

**Answer :- (3)**

**Q9. For a varying force work done can be expressed as a**

- definite integral of force over displacement
- differentiation of force with displacement
- product of force and displacement
- force divided by the displacement

**Answer :- (1)**

**Q10. If you drop a rubber ball from rest from a height of 3 m, what is the maximum height to which it will bounce back in the presence of air?**

- = 3 m
- > 3 m
- 4 m
- < 3 m

**Answer :- (4)**

**Q11. How much water a pump of 2 kW can raise in 1 minute to a height of 10 m, take g=10 m/s ^{2}.**

- 1000 litres
- 1200 litres
- 100 litres
- 2000 litres

**Answer :- (2)**

**Q12. A bomb of mass 4 kg explodes in air into two pieces of masses 3 kg and 1 kg. The smaller mass goes at a speed of 90 m/s. The total energy imparted to two fragments is.**

- 2.4 kJ
- 5.9 kJ
- 3.8 kJ
- 5.4 kJ

**Answer :- (4)**

**Q13. Which of the following statement is not related to conservative force?**

- Work done in closed path is zero
- Work done is recoverable
- Path dependent
- Path independent

**Answer :- (3)**

**Q14. Which of the following is correct?**

- 1 H.P = 55016 ft/s
- 1 H .P = 746 W
- Both A and B
- none of the above

**Answer :- (3)**

**Q15. Raindrops fall on the earth with certain kinetic energy on the earth. From where do they get this energy?**

- Gravitational Potential Energy
- Energy between molecules of water
- Chemical Energy
- Heat Energy

**Answer :- (1)**

**Q16. If only the conservative forces are acting on the body, then its total**

- Potential energy is conserved
- Kinetic energy is conserved
- Mechanical energy is conserved
- Either potential or kinetic energy could be conserved

**Answer :- (3)**

**Q17. A force is conservative if**

- the sum of the initial forces equals the final forces
- a constant force acts on the system
- work done over a closed path is zero
- work done for every path is zero

**Answer :- (3)**

**Q18. A force which does not depend on the path taken to increase the potential energy is**

- Conservative force
- Non-conservative force
- Frictional force
- Viscous force

**Answer :- (1)**

**Q19. A ball of mass 2 kg is raised to the height of 60 m and then dropped from the top. In this case, the quantity which has different magnitude from the other given quantities is**

- Work done by gravity
- Kinetic energy before hitting the ground
- Potential energy at the top
- Velocity just hitting the ground

**Answer :- (4)**

**Q20. Select the odd one out**

- Viscous force
- Air-resistance
- Electrostatic force
- Frictional force

**Answer :- (3)**

**Q21. Which of the following statements is false:**

- potential energy is negative
- kinetic energy is negative
- potential energy is positive
- kinetic energy is positive

**Answer :- (2)**

**Q22. What is the relationship between joule and erg?**

- 1 J = 10
^{7 }erg - 1 J = 10
^{4 }erg - 1 J = 10
^{5 }erg - 1 J = 10
^{8 }erg

**Answer :- (1)**

**Q23. An astronomer has total weight of 80 kg. On reaching moon, he climbs up 10 m to enter his aircraft by the ladder. His gravitational potential energy is increased by 1000 J. The value of the gravitational acceleration on the moon is**

- 1.25 N/kg
- 2 N/kg
- 2.25 kg
- 2.22 kg

**Answer :- (1)**

**Q24. Which of the following is not an example of zero work?**

- The work done by a coolie when he travels on a horizontal platform, with a load on his head.
- The work done by the tension in the string, when a body tied with the string move along a circular path.
- When a person holds some amount of load but, does not move from his position.
- When a horse pulls a cart on a level road.

**Answer :- (4)**

**Q25. Time rate at which work is done by a force is**

- Power
- Acceleration
- Torque
- Centrifugal Force

**Answer :- (1)**

**Q26. When conservative force does positive work on a body, the potential energy of the body:**

- increases
- decreases
- remains unaltered
- there is no relationship between force and potential energy

**Answer :- (2)**

**Q27. You are in a lift moving from the 3 ^{rd} floor to the 12^{th} floor, having a height difference of H = 40 m. Your mass is M = 80 kg and the acceleration due to gravity is g = 10 m/s^{2}. If the elevator moves at a constant speed without stopping, what is the total work performed by all of the forces together (the net force) acting on you?**

- MgH
- -MgH
- Mg
- 0

**Answer :- (4)**

**Q28. Work done by or against a conservative force in a round trip is**

- Maximum
- Minimum
- Zero
- May be maximum or zero

**Answer :- (3)**

**Q29. When a ball is allowed to fall from a height of 20 m, 40% of its energy is lost due to impact. After one impact the ball will go up to a height of**

- 10 m
- 8 m
- 12 m
- 15 m

**Answer :- (3)**

**Q30. In an elastic collision in one dimension if a body A collides against the body B of equal mass at rest, then the body A will**

- move with twice its initial velocity
- moves with the same velocity but in opposite direction.
- moves with the same velocity in the same direction.
- come to rest.

**Answer :- (4)**

**Q31.A plot of potential energy and kinetic energy versus displacement x for a block attached to a spring obeying Hooke’s law is**

- a parabola
- a straight line
- an ellipse
- a hyperbola

**Answer :- (1)**

**Q32. If the momentum of a body is doubled, then its kinetic energy will increase by**

- 50%
- 400%
- 300%
- 100%

**Answer :- (3)**

**Q33.If a ball of mass 1 kg makes a head-on collision with a ball of an unknown mass initially at rest such that the ball rebounds to one third of its original speed, what is the mass of the other ball?**

- 1 kg
- 3 kg
- 2 kg
- 4 kg

**Answer :- (3)**

**Q34. A hawk of mass 10 kg dives to catch a mouse. During dive it loses 500 J of its potential energy. The height from where it begins its dive is (take g = 10 m/s ^{2})**

- 50 m
- 10 m
- 5 m
- 1 m

**Answer :- (3)**

**Q35. The potential energy of a hammer of mass 10 kg, lifted to the height of 10 m is**

- 100 J
- 10 J
- 98 J
- 980 J

**Answer :- (4)**

**Q36. If momentum of an object is doubled, how does its kinetic energy change?**

- increases 4 times
- decreases 4 times
- increases 2 times
- decreases 2 times

**Answer :- (1)**

**Q37. The total mechanical energy of a system is conserved if the forces that act on it are**

- Non-conservative
- path dependent
- conservative
- frictional forces

**Answer :- (3)**

**Q38. Which of the following is not correct for the condition for work not to be done:**

- force is zero
- displacement is zero, though force is non-zero
- force and displacement are perpendicular to each other.
- force and displacement are at 180 degrees with each other

**Answer :- (4)**

**Q39. Frictional force is an example of**

- Non conservative force
- Conservative force
- Nuclear force
- Electrostatic force

**Answer :- (1)**

**Q40.The potential energy of the spring when stretched**

- Does not change
- Increases
- Decreases
- Depends on the material of the spring

**Answer :- (2)**