FSc Part 1 Physics chapter 2: Vectors and equilibrium MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

27 exam-style questions on Vectors and equilibrium, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

27 questions · 3 topics · 10 per test

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What chapter 2 covers

Ten Vectors and equilibrium questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Two equal and opposite forces act on a rod at different points, and their lines of action do not coincide. The rod will

  1. A
    remain at rest
  2. B
    accelerate in a straight line
  3. C
    rotate, because the net torque is not zero although the net force is zero
  4. D
    move in a straight line at constant velocity
Show answer

Answer: C. The forces form a couple: ΣF = 0 but Στ ≠ 0. The second condition of equilibrium fails, so the rod gains angular acceleration.

2. What is the unit vector in the direction of A = 3i + 4j?

  1. A
    3i + 4j
  2. B
    0.6i + 0.8j
  3. C
    0.75i + j
  4. D
    (3i + 4j)/7
Show answer

Answer: B. Unit vector = A/|A| = (3i + 4j)/5 = 0.6i + 0.8j, which has magnitude 1. Dividing by 7 adds the components instead of using Pythagoras.

3. The scalar product of two non-zero vectors is zero when the vectors are

  1. A
    parallel
  2. B
    anti-parallel
  3. C
    perpendicular
  4. D
    equal
Show answer

Answer: C. A · B = AB cos θ, which is zero when θ = 90°. Parallel vectors give the maximum value AB.

4. Which physical quantity is the scalar product of two vectors?

  1. A
    torque
  2. B
    angular momentum
  3. C
    power
  4. D
    velocity
Show answer

Answer: C. Power P = F · v is a dot product. Torque (r × F) and angular momentum (r × p) are cross products, which are vectors.

5. At what angle to the x-axis must a vector be drawn so that its x and y components are equal in magnitude?

  1. A
    0°
  2. B
    30°
  3. C
    45°
  4. D
    60°
Show answer

Answer: C. A cos θ = A sin θ when tan θ = 1, that is θ = 45°.

6. A 30 kg child sits 2.0 m from the pivot of a see-saw. Where must a 40 kg child sit on the other side to balance it?

  1. A
    1.2 m
  2. B
    1.5 m
  3. C
    2.0 m
  4. D
    2.7 m
Show answer

Answer: B. Clockwise moment = anticlockwise moment: 40g × d = 30g × 2.0, so d = 60/40 = 1.5 m. 2.7 m comes from inverting the ratio.

7. If A = 2i + 3j − k and B = i − 2j + 4k, then A · B equals

  1. A
    −8
  2. B
    8
  3. C
    0
  4. D
    −4
Show answer

Answer: A. A · B = (2)(1) + (3)(−2) + (−1)(4) = 2 − 6 − 4 = −8. A negative dot product means the angle between them is more than 90°.

8. When the first condition of equilibrium (ΣF = 0) is satisfied, a body

  1. A
    cannot rotate
  2. B
    must be at rest
  3. C
    has no linear acceleration
  4. D
    has zero net torque
Show answer

Answer: C. ΣF = 0 means translational equilibrium: no linear acceleration. The body may still be moving uniformly, or turning, if the torques do not balance.

9. A force F = 3j N acts at the point with position vector r = 2i m from the axis. The torque τ = r × F is

  1. A
    −6k N m
  2. B
    6k N m
  3. C
    6i N m
  4. D
    zero
Show answer

Answer: B. τ = (2i) × (3j) = 6(i × j) = 6k N m. Reversing the order (F × r) would give −6k.

10. Which statement about the vector (cross) product is correct?

  1. A
    A × B = B × A
  2. B
    A × A = A2
  3. C
    the magnitude of A × B is AB cos θ
  4. D
    A × B = −(B × A)
Show answer

Answer: D. The cross product is anti-commutative: A × B = −(B × A). A × A = 0 because sin 0° = 0, and the magnitude is AB sin θ.

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Ways to practise this chapter

Vectors and equilibrium: questions students ask

How many Vectors and equilibrium MCQs are there?

27, each with the answer and a short explanation, across 3 topics: Vectors: representation, addition and rectangular components, Product of two vectors, Torque and equilibrium. Every chapter test draws ten of them, so you can take it many times.

Is the FSc Part 1 Physics chapter 2 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

Can I read the explanations in Urdu?

Yes. In practice mode and on your results you can switch the explanations to Urdu.

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