LUMS LCAT Physics: Motion & Force MCQs

LUMS LCAT Physics: Motion & Force MCQs — sample questions

1. Question 1

   Q1. A 2 kg block is moving with 5 m/s velocity. What is its kinetic energy?

   • A) 25 J
   • B) 10 J
   • C) 20 J
   • D) 30 J

   Answer: 25 J

   Explanation: Kinetic energy = 1/2 mv² = 1/2 * 2 * 5² = 25 J, using the formula for kinetic energy.

2. Question 2

   Q2. A force of 10 N acts on a body of mass 2 kg. What is its acceleration?

   • A) 5 m/s²
   • B) 10 m/s²
   • C) 2 m/s²
   • D) 20 m/s²

   Answer: 5 m/s²

   Explanation: F = ma, so a = F/m = 10/2 = 5 m/s², applying Newton's second law.

3. Question 3

   Q3. A body is moving in a circular path. What is the direction of its acceleration?

   • A) Tangential to the circle
   • B) Perpendicular to the circle
   • C) Towards the center
   • D) Away from the center

   Answer: Towards the center

   Explanation: Centripetal acceleration is directed towards the center of the circle, necessary for circular motion.

4. Question 4

   Q4. A car accelerates from 0 to 60 km/h in 10 s. What is its average acceleration?

   • A) 1.67 m/s²
   • B) 6 m/s²
   • C) 16.7 m/s²
   • D) 0.6 m/s²

   Answer: 1.67 m/s²

   Explanation: First convert 60 km/h to m/s: 60 * 1000 / 3600 = 16.67 m/s. Then, a = Δv/Δt = 16.67 / 10 = 1.67 m/s².

5. Question 5

   Q5. A 5 kg block is pulled with a force of 20 N at 30° to the horizontal. What is its horizontal acceleration?

   • A) 3.46 m/s²
   • B) 2 m/s²
   • C) 4 m/s²
   • D) 1.73 m/s²

   Answer: 3.46 m/s²

   Explanation: Horizontal component of force = Fcos(30°) = 20 * √3 / 2 = 17.32 N. Then, a = F/m = 17.32 / 5 = 3.46 m/s².

6. Question 6

   Q6. A body is thrown upwards with 20 m/s. What is its velocity at the highest point?

   • A) 0 m/s
   • B) 10 m/s
   • C) 20 m/s
   • D) -10 m/s

   Answer: 0 m/s

   Explanation: At the highest point, velocity is 0 m/s because the body momentarily stops before falling back.

7. Question 7

   Q7. A force of 5 N acts on a body for 4 s. What is the impulse?

   • A) 10 Ns
   • B) 20 Ns
   • C) 15 Ns
   • D) 25 Ns

   Answer: 20 Ns

   Explanation: Impulse = F * Δt = 5 * 4 = 20 Ns, using the formula for impulse.

8. Question 8

   Q8. A 10 kg block is moving on a frictionless surface. What is its acceleration if a 20 N force is applied?

   • A) 2 m/s²
   • B) 1 m/s²
   • C) 4 m/s²
   • D) 0.5 m/s²

   Answer: 2 m/s²

   Explanation: F = ma, so a = F/m = 20/10 = 2 m/s², applying Newton's second law.

9. Question 9

   Q9. A body is moving in a straight line with uniform velocity. What is its acceleration?

   • A) 0 m/s²
   • B) 1 m/s²
   • C) -1 m/s²
   • D) 2 m/s²

   Answer: 0 m/s²

   Explanation: Uniform velocity means zero acceleration because there's no change in velocity.

10. Question 10

    Q10. A 2 kg block is attached to a spring with spring constant 100 N/m. What is its angular frequency?

    • A) √50 rad/s
    • B) 10 rad/s
    • C) 5 rad/s
    • D) 20 rad/s

    Answer: √50 rad/s

    Explanation: ω = √(k/m) = √(100/2) = √50 rad/s, using the formula for angular frequency of a spring-mass system.

11. Question 11

    Q11. A car is moving on a circular track. What is the direction of the frictional force?

    • A) Towards the center
    • B) Away from the center
    • C) Tangential to the circle
    • D) Perpendicular to the circle

    Answer: Towards the center

    Explanation: Frictional force provides the necessary centripetal force, directing towards the center.

12. Question 12

    Q12. A body is projected at 45° to the horizontal. What is its range?

    • A) v² / g
    • B) v²sin(2θ) / g
    • C) v²sin(θ) / g
    • D) v²cos(θ) / g

    Answer: v²sin(2θ) / g

    Explanation: Range = v²sin(2θ) / g. At 45°, sin(2θ) = 1, so range = v² / g, using the range formula.

13. Question 13

    Q13. A 5 kg block is moving with 10 m/s velocity. What is its momentum?

    • A) 50 kg m/s
    • B) 25 kg m/s
    • C) 10 kg m/s
    • D) 100 kg m/s

    Answer: 50 kg m/s

    Explanation: Momentum = mv = 5 * 10 = 50 kg m/s, using the formula for momentum.

14. Question 14

    Q14. A force of 10 N is applied to a body of mass 5 kg. What is its acceleration?

    • A) 2 m/s²
    • B) 1 m/s²
    • C) 5 m/s²
    • D) 0.5 m/s²

    Answer: 2 m/s²

    Explanation: F = ma, so a = F/m = 10/5 = 2 m/s², applying Newton's second law.

15. Question 15

    Q15. A body is moving in a circular path with constant speed. What is its acceleration?

    • A) 0 m/s²
    • B) v² / r
    • C) v / r
    • D) -v² / r

    Answer: v² / r

    Explanation: Centripetal acceleration = v² / r, necessary for circular motion with constant speed.

16. Question 16

    Q16. A 10 kg block is pulled up a frictionless incline. What is its acceleration?

    • A) g sin(θ)
    • B) g cos(θ)
    • C) g tan(θ)
    • D) 0

    Answer: g sin(θ)

    Explanation: Acceleration down the incline = g sin(θ), due to the component of gravity along the incline.

17. Question 17

    Q17. A body is thrown upwards. What is its acceleration?

    • A) g
    • B) -g
    • C) 0
    • D) 2g

    Answer: g

    Explanation: Acceleration due to gravity = g, always downwards, regardless of the body's direction.

18. Question 18

    Q18. A car accelerates from rest to 20 m/s in 4 s. What is its average acceleration?

    • A) 5 m/s²
    • B) 4 m/s²
    • C) 10 m/s²
    • D) 2 m/s²

    Answer: 5 m/s²

    Explanation: a = Δv/Δt = 20 / 4 = 5 m/s², using the formula for average acceleration.

19. Question 19

    Q19. A 2 kg block is moving on a horizontal surface with a frictional force of 4 N. What is its acceleration?

    • A) -2 m/s²
    • B) 2 m/s²
    • C) -1 m/s²
    • D) 1 m/s²

    Answer: -2 m/s²

    Explanation: F = ma, so a = -F/m = -4/2 = -2 m/s², negative because friction opposes motion.

20. Question 20

    Q20. A body is moving with uniform acceleration. What is its velocity at time t?

    • A) u + at
    • B) u - at
    • C) v + at
    • D) v - at

    Answer: u + at

    Explanation: v = u + at, using the equation of motion for uniform acceleration.