MDCAT Physics: Work and Energy MCQs

MDCAT Physics: Work and Energy MCQs

1. Question 1

   Q1. A force of 10 N acts on a body, displacing it by 2 m in the direction of the force. What is the work done?

   • A) 5 J
   • B) 10 J
   • C) 20 J
   • D) 40 J

   Answer: 20 J

   Explanation: Work done is calculated as force times displacement in the direction of the force, so 10 N * 2 m = 20 J.

2. Question 2

   Q2. The energy of a body due to its motion is called

   • A) Potential energy
   • B) Kinetic energy
   • C) Mechanical energy
   • D) Thermal energy

   Answer: Kinetic energy

   Explanation: Kinetic energy is the energy of motion, whereas potential energy is stored energy.

3. Question 3

   Q3. A 2 kg object is moving at a speed of 4 m/s. What is its kinetic energy?

   • A) 4 J
   • B) 8 J
   • C) 16 J
   • D) 32 J

   Answer: 16 J

   Explanation: Kinetic energy = 0.5 * m * v^2 = 0.5 * 2 kg * (4 m/s)^2 = 16 J.

4. Question 4

   Q4. The unit of energy in the SI system is

   • A) Joule
   • B) Watt
   • C) Newton
   • D) Pascal

   Answer: Joule

   Explanation: Joule is the SI unit of energy, whereas Watt is the unit of power.

5. Question 5

   Q5. A body is lifted to a height of 10 m. What type of energy does it possess at this height?

   • A) Kinetic energy
   • B) Potential energy
   • C) Thermal energy
   • D) Electrical energy

   Answer: Potential energy

   Explanation: At a height, the body possesses potential energy due to its position.

6. Question 6

   Q6. The work-energy theorem states that the net work done on an object is equal to its change in

   • A) Potential energy
   • B) Kinetic energy
   • C) Momentum
   • D) Acceleration

   Answer: Kinetic energy

   Explanation: The work-energy theorem relates net work done to the change in kinetic energy.

7. Question 7

   Q7. A 5 kg block is pulled up a frictionless incline to a height of 3 m. What is the work done?

   • A) 150 J
   • B) 147 J
   • C) 150 N
   • D) 0 J

   Answer: 150 J

   Explanation: Work done = m * g * h = 5 kg * 9.8 m/s^2 * 3 m = 147 J, closest answer is 150 J.

8. Question 8

   Q8. The rate of doing work is called

   • A) Energy
   • B) Power
   • C) Force
   • D) Momentum

   Answer: Power

   Explanation: Power is the rate at which work is done or energy is transferred.

9. Question 9

   Q9. A machine does 100 J of work in 5 seconds. What is its power?

   • A) 20 W
   • B) 50 W
   • C) 100 W
   • D) 500 W

   Answer: 20 W

   Explanation: Power = work / time = 100 J / 5 s = 20 W.

10. Question 10

    Q10. The law of conservation of energy states that energy cannot be

    • A) Created
    • B) Destroyed
    • C) Transformed
    • D) Both A and B

    Answer: Both A and B

    Explanation: Energy cannot be created or destroyed, only transformed from one form to another.

11. Question 11

    Q11. A ball is thrown upwards. At the highest point, its energy is entirely

    • A) Kinetic
    • B) Potential
    • C) Thermal
    • D) Both kinetic and potential

    Answer: Potential

    Explanation: At the highest point, the ball's energy is entirely potential due to its height.

12. Question 12

    Q12. The energy stored in a stretched spring is an example of

    • A) Kinetic energy
    • B) Potential energy
    • C) Thermal energy
    • D) Electrical energy

    Answer: Potential energy

    Explanation: A stretched spring stores potential energy due to its elastic deformation.

13. Question 13

    Q13. A force of 20 N acts on a body at an angle of 60 degrees to its direction of motion. If the body moves 5 m, what is the work done?

    • A) 25 J
    • B) 50 J
    • C) 75 J
    • D) 100 J

    Answer: 50 J

    Explanation: Work done = F * d * cos(θ) = 20 N * 5 m * cos(60°) = 20 * 5 * 0.5 = 50 J.

14. Question 14

    Q14. A body of mass 10 kg is moving with a velocity of 2 m/s. Its kinetic energy is

    • A) 10 J
    • B) 20 J
    • C) 40 J
    • D) 200 J

    Answer: 20 J

    Explanation: Kinetic energy = 0.5 * m * v^2 = 0.5 * 10 kg * (2 m/s)^2 = 20 J.

15. Question 15

    Q15. A car accelerates from rest to a speed of 20 m/s. If its mass is 1500 kg, what is the work done?

    • A) 150 kJ
    • B) 300 kJ
    • C) 450 kJ
    • D) 600 kJ

    Answer: 300 kJ

    Explanation: Work done = change in kinetic energy = 0.5 * m * (v_f^2 - v_i^2) = 0.5 * 1500 kg * (20 m/s)^2 = 300,000 J = 300 kJ.

16. Question 16

    Q16. A 50 N force is applied to a body, causing it to move 4 m in 2 seconds. What is the average power delivered?

    • A) 25 W
    • B) 50 W
    • C) 100 W
    • D) 200 W

    Answer: 100 W

    Explanation: Work done = F * d = 50 N * 4 m = 200 J, Power = work / time = 200 J / 2 s = 100 W.

17. Question 17

    Q17. The potential energy of a body at a height of 5 m is 245 J. What is its mass?

    • A) 2 kg
    • B) 5 kg
    • C) 10 kg
    • D) 20 kg

    Answer: 5 kg

    Explanation: Potential energy = m * g * h, so m = PE / (g * h) = 245 J / (9.8 m/s^2 * 5 m) = 5 kg.

18. Question 18

    Q18. A body is moving in a circular path at a constant speed. What is the work done by the centripetal force?

    • A) Positive
    • B) Negative
    • C) Zero
    • D) Depends on the radius

    Answer: Zero

    Explanation: The centripetal force is perpendicular to the direction of motion, so the work done is zero.

19. Question 19

    Q19. A 10 kg block is lifted to a height of 2 m in 4 seconds. What is the average power used?

    • A) 49 W
    • B) 50 W
    • C) 98 W
    • D) 100 W

    Answer: 49 W

    Explanation: Work done = m * g * h = 10 kg * 9.8 m/s^2 * 2 m = 196 J, Power = work / time = 196 J / 4 s = 49 W.

20. Question 20

    Q20. A spring with a spring constant of 100 N/m is compressed by 0.2 m. What is the potential energy stored?

    • A) 1 J
    • B) 2 J
    • C) 4 J
    • D) 8 J

    Answer: 2 J

    Explanation: Potential energy = 0.5 * k * x^2 = 0.5 * 100 N/m * (0.2 m)^2 = 2 J.