Class 9 Science Chapter 7 MCQs – Work, Energy, and Simple Machines provides 50 important multiple-choice questions with answers for exam preparation and concept revision. These MCQs cover work, energy, kinetic energy, potential energy, power, conservation of energy, simple machines, levers, pulleys, and mechanical advantage.
1. In physics, work is said to be done when:
A. A force acts on an object without displacement
B. An object undergoes displacement due to a force
C. An object is at rest
D. Only energy is present
Answer: B. An object undergoes displacement due to a force
2. The SI unit of work is:
A. Newton
B. Joule
C. Watt
D. Pascal
Answer: B. Joule
3. One joule of work is done when a force of 1 N:
A. Acts for 1 second
B. Produces a displacement of 1 m in its direction
C. Produces a displacement of 1 cm
D. Acts on a mass of 1 kg
Answer: B. Produces a displacement of 1 m in its direction
4. The mathematical expression for work done by a constant force in the direction of displacement is:
A. W = F/d
B. W = F + d
C. W = Fd
D. W = d/F
Answer: C. W = Fd
5. If a force acts on an object but the object does not move, the work done is:
A. Maximum
B. Minimum
C. Zero
D. Infinite
Answer: C. Zero
6. A person pushes a wall with great force, but the wall does not move. The work done on the wall is:
A. Zero
B. Maximum
C. Equal to the force applied
D. Infinite
Answer: A. Zero
7. When force and displacement are in the same direction, the work done is:
A. Positive
B. Negative
C. Zero
D. Always infinite
Answer: A. Positive
8. When force acts opposite to the direction of displacement, the work done is:
A. Positive
B. Negative
C. Zero
D. Always maximum
Answer: B. Negative
9. The work done by the gravitational force on a body moving upward is generally:
A. Positive
B. Negative
C. Zero
D. Infinite
Answer: B. Negative
10. Which of the following is an example of positive work?
A. Friction acting on a sliding object
B. Gravity acting on a falling object
C. A person lifting an object upward
D. A person pushing a wall that does not move
Answer: B. Gravity acting on a falling object
11. Energy is defined as the:
A. Ability to do work
B. Rate of doing work only
C. Force acting on an object
D. Distance travelled by an object
Answer: A. Ability to do work
12. The SI unit of energy is:
A. Newton
B. Joule
C. Watt
D. Metre
Answer: B. Joule
13. The energy possessed by an object due to its motion is called:
A. Potential energy
B. Chemical energy
C. Kinetic energy
D. Nuclear energy
Answer: C. Kinetic energy
14. The kinetic energy of an object depends on:
A. Its mass and velocity
B. Its height only
C. Its volume only
D. Its colour
Answer: A. Its mass and velocity
15. The formula for kinetic energy is:
A. KE = mv
B. KE = mgh
C. KE = ½mv²
D. KE = Fd
Answer: C. KE = ½mv²
16. If the velocity of an object is doubled, its kinetic energy becomes:
A. Two times
B. Half
C. Four times
D. Eight times
Answer: C. Four times
17. If the mass of an object is doubled while its velocity remains constant, its kinetic energy becomes:
A. Half
B. Double
C. Four times
D. Unchanged
Answer: B. Double
18. A body of mass 2 kg is moving with a velocity of 3 m/s. Its kinetic energy is:
A. 3 J
B. 6 J
C. 9 J
D. 18 J
Answer: C. 9 J
19. A 4 kg object moves with a velocity of 5 m/s. Its kinetic energy is:
A. 20 J
B. 40 J
C. 50 J
D. 100 J
Answer: C. 50 J
20. The energy possessed by an object because of its position or configuration is called:
A. Kinetic energy
B. Potential energy
C. Sound energy
D. Electrical energy
Answer: B. Potential energy
21. The gravitational potential energy of an object depends on:
A. Mass, gravitational acceleration and height
B. Mass and velocity only
C. Force and time only
D. Distance travelled only
Answer: A. Mass, gravitational acceleration and height
22. The formula for gravitational potential energy is:
A. PE = ½mv²
B. PE = F/t
C. PE = mgh
D. PE = mv
Answer: C. PE = mgh
23. If the height of an object above the ground is doubled, its gravitational potential energy becomes:
A. Half
B. Double
C. Four times
D. Unchanged
Answer: B. Double
24. A 2 kg object is raised to a height of 5 m. Taking g = 10 m/s², its potential energy is:
A. 10 J
B. 25 J
C. 50 J
D. 100 J
Answer: D. 100 J
25. Which of the following has both kinetic and potential energy?
A. A stationary stone lying on the ground
B. A moving ball at a height above the ground
C. A book lying on a table
D. A stationary object at ground level
Answer: B. A moving ball at a height above the ground
26. The law of conservation of energy states that energy:
A. Can be created but not destroyed
B. Can be destroyed but not created
C. Can neither be created nor destroyed, but can change from one form to another
D. Always remains as kinetic energy
Answer: C. Can neither be created nor destroyed, but can change from one form to another
27. When a ball falls from a height, its:
A. Potential energy increases and kinetic energy decreases
B. Potential energy decreases and kinetic energy increases
C. Both energies decrease
D. Both energies remain zero
Answer: B. Potential energy decreases and kinetic energy increases
28. In the absence of air resistance, the total mechanical energy of a freely falling object:
A. Increases continuously
B. Decreases continuously
C. Remains constant
D. Becomes zero
Answer: C. Remains constant
29. The energy stored in a stretched rubber band is mainly:
A. Kinetic energy
B. Elastic potential energy
C. Nuclear energy
D. Sound energy
Answer: B. Elastic potential energy
30. A stretched spring possesses:
A. Potential energy
B. Only kinetic energy
C. No energy
D. Only sound energy
Answer: A. Potential energy
31. Power is defined as:
A. Work done per unit time
B. Force per unit distance
C. Energy per unit mass
D. Distance per unit time
Answer: A. Work done per unit time
32. The SI unit of power is:
A. Joule
B. Newton
C. Watt
D. Kilowatt-hour
Answer: C. Watt
33. One watt is equal to:
A. One joule per second
B. One newton per second
C. One joule per metre
D. One kilogram per second
Answer: A. One joule per second
34. A machine does 500 J of work in 10 seconds. Its power is:
A. 5 W
B. 50 W
C. 100 W
D. 5000 W
Answer: B. 50 W
35. Two machines perform the same amount of work. The machine that performs it in less time has:
A. Less power
B. More power
C. No power
D. Equal power always
Answer: B. More power
36. A simple machine is a device that:
A. Creates energy
B. Makes work easier by changing the magnitude or direction of force
C. Destroys energy
D. Always increases the amount of work done
Answer: B. Makes work easier by changing the magnitude or direction of force
37. Which of the following is a simple machine?
A. Lever
B. Electric motor
C. Battery
D. Television
Answer: A. Lever
38. Which of the following is an example of a lever?
A. Seesaw
B. Electric bulb
C. Battery
D. Refrigerator
Answer: A. Seesaw
39. A lever consists mainly of:
A. Fulcrum, load and effort
B. Battery, wire and bulb
C. Mass, volume and density
D. Magnet, coil and switch
Answer: A. Fulcrum, load and effort
40. The fixed point around which a lever turns is called:
A. Load
B. Effort
C. Fulcrum
D. Resistance
Answer: C. Fulcrum
41. In a first-class lever, the:
A. Load lies between effort and fulcrum
B. Effort lies between load and fulcrum
C. Fulcrum lies between effort and load
D. Fulcrum is absent
Answer: C. Fulcrum lies between effort and load
42. Which of the following is an example of a first-class lever?
A. Seesaw
B. Wheelbarrow
C. Tweezers
D. Fishing rod
Answer: A. Seesaw
43. In a second-class lever, the:
A. Fulcrum lies between effort and load
B. Load lies between fulcrum and effort
C. Effort lies between fulcrum and load
D. Load is absent
Answer: B. Load lies between fulcrum and effort
44. Which of the following is an example of a second-class lever?
A. Scissors
B. Wheelbarrow
C. Tweezers
D. Human forearm
Answer: B. Wheelbarrow
45. In a third-class lever, the:
A. Fulcrum lies between load and effort
B. Load lies between fulcrum and effort
C. Effort lies between fulcrum and load
D. Fulcrum is absent
Answer: C. Effort lies between fulcrum and load
46. Which of the following is an example of a third-class lever?
A. Seesaw
B. Wheelbarrow
C. Tweezers
D. Crowbar
Answer: C. Tweezers
47. Mechanical advantage is defined as:
A. Load / Effort
B. Effort / Load
C. Work / Time
D. Distance / Time
Answer: A. Load / Effort
48. If a machine lifts a load of 600 N using an effort of 200 N, its mechanical advantage is:
A. 2
B. 3
C. 4
D. 6
Answer: B. 3
49. Which simple machine consists of a wheel with a groove around its edge through which a rope or cable passes?
A. Lever
B. Pulley
C. Inclined plane
D. Screw
Answer: B. Pulley
50. Which statement about a simple machine is correct?
A. A machine can create energy
B. A machine can reduce the total work required below the input work in an ideal system
C. A machine can make work easier by changing the magnitude or direction of force
D. A machine always produces more energy than supplied
Answer: C. A machine can make work easier by changing the magnitude or direction of force