Work, Energy and Simple Machines
MCQs
1. Work is said to be done when:
A. Force acts without displacement
B. Displacement occurs without force
C. Force causes displacement
D. An object remains at rest
Answer: C
2. The SI unit of work is:
A. Newton
B. Joule
C. Watt
D. Pascal
Answer: B
3. One joule is equal to:
A. 1 N/m
B. 1 N × m
C. 1 kg/m
D. 1 W/s
Answer: B
4. Work done by a force is zero when:
A. Force is large
B. Displacement is large
C. No displacement occurs
D. Velocity is constant
Answer: C
5. A girl carries a school bag horizontally on a road. The work done by the upward force on the bag is:
A. Positive
B. Negative
C. Zero
D. Infinite
Answer: C
6. Positive work is done when force and displacement are:
A. Opposite
B. Perpendicular
C. In same direction
D. Zero
Answer: C
7. Negative work is done when force and displacement are:
A. Same direction
B. Opposite direction
C. Perpendicular
D. Equal
Answer: B
8. Friction generally does:
A. Positive work
B. Negative work
C. Zero work always
D. Infinite work
Answer: B
9. Energy is defined as:
A. Rate of doing work
B. Capacity to do work
C. Force × velocity
D. Mass × acceleration
Answer: B
10. According to the work-energy theorem:
A. Work done = force × acceleration
B. Work done = change in energy
C. Energy = power × time only
D. Work done = mass × velocity
Answer: B
11. The SI unit of energy is:
A. Joule
B. Newton
C. Watt
D. Pascal
Answer: A
12. The energy possessed by an object due to motion is:
A. Potential energy
B. Mechanical energy
C. Kinetic energy
D. Chemical energy
Answer: C
13. The kinetic energy of an object depends on:
A. Mass only
B. Velocity only
C. Both mass and velocity
D. Shape only
Answer: C
14. The formula for kinetic energy is:
A. (mv)
B. (mgh)
C. (\frac{1}{2}mv^2)
D. (F/s)
Answer: C
15. If the speed of an object doubles, its kinetic energy becomes:
A. Double
B. Four times
C. Half
D. Eight times
Answer: B
16. The energy stored due to position or configuration is:
A. Kinetic energy
B. Electrical energy
C. Potential energy
D. Heat energy
Answer: C
17. Gravitational potential energy depends on:
A. Mass, height, and gravity
B. Velocity only
C. Speed and force
D. Time only
Answer: A
18. Formula for gravitational potential energy:
A. (mv^2)
B. (mgh)
C. (ma)
D. (Fs)
Answer: B
19. Mechanical energy is the sum of:
A. Heat and sound energy
B. Kinetic and potential energy
C. Chemical and electrical energy
D. Light and heat energy
Answer: B
20. According to conservation of mechanical energy:
A. Mechanical energy always decreases
B. Mechanical energy always increases
C. Total mechanical energy remains constant if no external force acts
D. Potential energy remains constant always
Answer: C
21. At the highest point of a freely falling object:
A. Kinetic energy is maximum
B. Potential energy is maximum
C. Both are zero
D. Mechanical energy is zero
Answer: B
22. At the lowest point during free fall:
A. Potential energy is maximum
B. Kinetic energy is minimum
C. Kinetic energy is maximum
D. Both energies are equal to zero
Answer: C
23. Power is:
A. Work done × time
B. Work done per unit time
C. Energy × force
D. Force per unit area
Answer: B
24. The SI unit of power is:
A. Joule
B. Newton
C. Watt
D. Pascal
Answer: C
25. One watt equals:
A. 1 J/s
B. 1 N/s
C. 1 J × s
D. 1 kg m/s
Answer: A
26. A machine that changes direction of force is:
A. Lever
B. Inclined plane
C. Pulley
D. Wedge
Answer: C
27. Mechanical advantage is:
A. Effort/load
B. Load/effort
C. Force × displacement
D. Work/time
Answer: B
28. A fixed pulley has mechanical advantage:
A. 0
B. 1
C. 2
D. More than 2
Answer: B
29. An inclined plane helps by:
A. Increasing load
B. Reducing distance
C. Reducing effort force
D. Increasing weight
Answer: C
30. Roads in hilly areas are zig-zag because:
A. Distance becomes shorter
B. Effort required decreases
C. Gravity disappears
D. Speed increases automatically
Answer: B
Assertion–Reason MCQs
31.
Assertion (A): Carrying a load horizontally may involve zero work done on the load.
Reason (R): Force and displacement are perpendicular.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
32.
Assertion (A): Kinetic energy increases with speed.
Reason (R): Kinetic energy is proportional to square of velocity.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
33.
Assertion (A): Mechanical energy remains constant during free fall.
Reason (R): Potential energy converts into kinetic energy.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
34.
Assertion (A): A fixed pulley reduces effort force.
Reason (R): It changes direction of force only.
A. Both A and R are true, and R explains A
B. A is false but R is true
C. A is true but R is false
D. Both are false
Answer: B
Case-Based MCQs
Case Study 1
A child slides down from a playground slide of height h.
35. At the top of the slide, the child mainly possesses:
A. Kinetic energy
B. Potential energy
C. Sound energy
D. Heat energy
Answer: B
36. During sliding down:
A. Potential energy increases
B. Kinetic energy decreases
C. Potential energy converts into kinetic energy
D. Mechanical energy disappears
Answer: C
37. Ignoring friction, the speed at the bottom depends mainly on:
A. Mass only
B. Shape of slide only
C. Height of slide
D. Color of slide
Answer: C
Case Study 2
A worker pushes a heavy box using an inclined ramp.
38. The inclined plane helps by:
A. Increasing effort
B. Reducing force needed
C. Increasing load
D. Reducing distance traveled
Answer: B
39. If the ramp length increases:
A. Required effort decreases
B. Required effort increases
C. Mechanical advantage becomes zero
D. Height decreases automatically
Answer: A
Competency-Based MCQs
40. A body of mass 2 kg moves with speed 3 m/s. Its kinetic energy is:
A. 3 J
B. 6 J
C. 9 J
D. 18 J
Answer: C
41. A 5 kg object is raised to a height of 10 m. Take (g = 10,m/s^2). Its potential energy is:
A. 50 J
B. 100 J
C. 250 J
D. 500 J
Answer: D
42. A machine with load 200 N and effort 50 N has mechanical advantage:
A. 2
B. 3
C. 4
D. 5
Answer: C
43. A person does 600 J work in 3 seconds. Power developed is:
A. 100 W
B. 150 W
C. 200 W
D. 300 W
Answer: C
44. Which situation involves negative work?
A. Pulling a cart forward
B. Gravity acting on a falling object
C. Friction slowing a moving bicycle
D. Lifting a bucket upward
Answer: C
45. A spring stores energy when:
A. It is at rest only
B. It is stretched or compressed
C. It moves with constant speed
D. It loses mass
Answer: B
46. Which energy conversion occurs in a pendulum as it swings downward?
A. Kinetic → Potential
B. Potential → Kinetic
C. Heat → Sound
D. Sound → Light
Answer: B
47. Which machine changes only the direction of force?
A. Inclined plane
B. Lever
C. Fixed pulley
D. Screw
Answer: C
48. The work done by gravity on a freely falling object is:
A. Negative
B. Positive
C. Zero
D. Infinite
Answer: B
49. Which quantity remains conserved in ideal free fall?
A. Power
B. Force
C. Mechanical energy
D. Momentum only
Answer: C
50. Why does a longer ramp make lifting easier?
A. It increases load
B. It decreases height
C. It reduces effort force needed
D. It reduces work done
Answer: C
