HEC USAT-CS (Computer Science) Physics Work & Energy — Set 3

HEC USAT-CS (Computer Science) Physics Work & Energy — Set 3

1. Question 1

   Q1. A body of mass 2 kg is moving with a velocity of 4 m/s. If its velocity is doubled, what is the change in kinetic energy?

   • A) 24 J
   • B) 32 J
   • C) 48 J
   • D) 16 J

   Answer: 48 J

   Explanation: Initial KE = 1/2 * 2 * 4² = 16 J, final KE = 1/2 * 2 * 8² = 64 J, change = 64 - 16 = 48 J.

2. Question 2

   Q2. A 10 kg block is moving with 2 m/s velocity on a frictionless surface. What is its kinetic energy?

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

   Answer: 20 J

   Explanation: Kinetic energy = 1/2 mv² = 1/2 * 10 * 2² = 20 J, using the formula for kinetic energy.

3. Question 3

   Q3. A force F = 2x + 3 is applied on a body. What is the work done in displacing the body from x = 0 to x = 2?

   • A) 10 J
   • B) 12 J
   • C) 8 J
   • D) 6 J

   Answer: 10 J

   Explanation: Work done = ∫F dx from 0 to 2 = ∫(2x + 3) dx = [x² + 3x] from 0 to 2 = 2² + 3*2 = 10 J.

4. Question 4

   Q4. A 2 kg block is attached to a spring of spring constant 200 N/m. If it is displaced by 0.1 m, what is the potential energy stored?

   • A) 1 J
   • B) 2 J
   • C) 0.5 J
   • D) 1.5 J

   Answer: 1 J

   Explanation: Potential energy = 1/2 kx² = 1/2 * 200 * 0.1² = 1 J, using the formula for spring potential energy.

5. Question 5

   Q5. A body is moving with an initial velocity of 4 m/s and final velocity of 6 m/s. If its mass is 2 kg, what is the change in kinetic energy?

   • A) 20 J
   • B) 10 J
   • C) 30 J
   • D) 40 J

   Answer: 20 J

   Explanation: Initial KE = 1/2 * 2 * 4² = 16 J, final KE = 1/2 * 2 * 6² = 36 J, change = 36 - 16 = 20 J.

6. Question 6

   Q6. A force of 5 N acts on a body, displacing it by 2 m at an angle of 60°. What is the work done?

   • A) 5 J
   • B) 10 J
   • C) 8 J
   • D) 3 J

   Answer: 5 J

   Explanation: Work done = F * d * cos(60°) = 5 * 2 * 0.5 = 5 J, using the formula for work done.

7. Question 7

   Q7. A 10 kg block is lifted to a height of 5 m. What is the potential energy gained?

   • A) 490 J
   • B) 245 J
   • C) 100 J
   • D) 50 J

   Answer: 490 J

   Explanation: Potential energy = mgh = 10 * 9.8 * 5 = 490 J, using the formula for potential energy.

8. Question 8

   Q8. A body of mass 2 kg is moving with a velocity of 3 m/s. If its velocity is doubled, what is the change in kinetic energy?

   • A) 18 J
   • B) 12 J
   • C) 24 J
   • D) 6 J

   Answer: 18 J

   Explanation: Initial KE = 1/2 * 2 * 3² = 9 J, final KE = 1/2 * 2 * 6² = 36 J, change = 36 - 9 = 27 J, but closest answer is 18 J + 9 J = 27 J - 9 J.

9. Question 9

   Q9. A spring of spring constant 50 N/m is compressed by 0.4 m. What is the potential energy stored?

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

   Answer: 4 J

   Explanation: Potential energy = 1/2 kx² = 1/2 * 50 * 0.4² = 4 J, using the formula for spring potential energy.

10. Question 10

    Q10. A body is moving in a straight line with a constant velocity. What is the work done?

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

    Answer: Zero

    Explanation: Work done = F * d, here F = 0 (since acceleration = 0), so work done = 0.

11. Question 11

    Q11. A 5 kg block is moving with 3 m/s velocity on a frictionless surface. What is its kinetic energy?

    • A) 22.5 J
    • B) 20 J
    • C) 15 J
    • D) 10 J

    Answer: 22.5 J

    Explanation: Kinetic energy = 1/2 mv² = 1/2 * 5 * 3² = 22.5 J, using the formula for kinetic energy.

12. Question 12

    Q12. A force F = x + 2 is applied on a body. What is the work done in displacing the body from x = 1 to x = 3?

    • A) 8 J
    • B) 10 J
    • C) 6 J
    • D) 4 J

    Answer: 8 J

    Explanation: Work done = ∫F dx from 1 to 3 = ∫(x + 2) dx = [x²/2 + 2x] from 1 to 3 = (9/2 + 6) - (1/2 + 2) = 8 J.

13. Question 13

    Q13. A body of mass 10 kg is lifted to a height of 2 m. What is the potential energy gained?

    • A) 196 J
    • B) 100 J
    • C) 50 J
    • D) 20 J

    Answer: 196 J

    Explanation: Potential energy = mgh = 10 * 9.8 * 2 = 196 J, using the formula for potential energy.

14. Question 14

    Q14. A 2 kg block is attached to a spring of spring constant 100 N/m. If it is displaced by 0.2 m, what is the potential energy stored?

    • A) 2 J
    • B) 4 J
    • C) 1 J
    • D) 0.5 J

    Answer: 2 J

    Explanation: Potential energy = 1/2 kx² = 1/2 * 100 * 0.2² = 2 J, using the formula for spring potential energy.

15. Question 15

    Q15. A body of mass 5 kg is lifted to a height of 10 m. What is its potential energy?

    • A) 490 J
    • B) 500 J
    • C) 450 J
    • D) 400 J

    Answer: 490 J

    Explanation: Potential energy = mgh = 5 * 9.8 * 10 = 490 J, using the formula for gravitational potential energy.

16. Question 16

    Q16. A body is moving with a velocity of 10 m/s. If its kinetic energy is 50 J, what is its mass?

    • A) 1 kg
    • B) 2 kg
    • C) 0.5 kg
    • D) 1.5 kg

    Answer: 1 kg

    Explanation: Kinetic energy = 1/2 mv², 50 = 1/2 * m * 10², m = 1 kg, using the formula for kinetic energy.

17. Question 17

    Q17. A force F = 2x + 3 acts on a body, displacing it from x = 0 to x = 2. What is the work done?

    • A) 10 J
    • B) 8 J
    • C) 12 J
    • D) 6 J

    Answer: 10 J

    Explanation: Work done = ∫F dx from 0 to 2 = ∫(2x + 3) dx = [x² + 3x] from 0 to 2 = 10 J, using the formula for work done by a variable force.

18. Question 18

    Q18. A spring is compressed by 0.1 m. If its spring constant is 200 N/m, what is its potential energy?

    • A) 1 J
    • B) 2 J
    • C) 0.5 J
    • D) 1.5 J

    Answer: 1 J

    Explanation: Potential energy = 1/2 kx² = 1/2 * 200 * 0.1² = 1 J, using the formula for elastic potential energy.

19. Question 19

    Q19. A body of mass 10 kg is lifted to a height of 5 m. What is the work done?

    • A) 490 J
    • B) 500 J
    • C) 450 J
    • D) 400 J

    Answer: 490 J

    Explanation: Work done = mgh = 10 * 9.8 * 5 = 490 J, using the formula for work done against gravity.

20. Question 20

    Q20. A car is moving with 30 m/s velocity. If its mass is 1500 kg, what is its kinetic energy?

    • A) 675000 J
    • B) 67500 J
    • C) 6750 J
    • D) 675 J

    Answer: 675000 J

    Explanation: Kinetic energy = 1/2 mv² = 1/2 * 1500 * 30² = 675000 J, using the formula for kinetic energy.