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Quiz Chapter 1: Force and Motion II

10 questions · Form 5 Physics Bab 1: Force and Motion II

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Four identical springs with constant k are configured as two parallel pairs, and these two pairs are connected in series. What is the effective spring constant of the combined system?

  1. k2
  2. 4k
  3. k
  4. 2k
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Answer: C

Each parallel pair has keff1 = 2k. Connecting two 2k systems in series gives 1/ktotal = 12k + 12k = 22k = 1k => ktotal = k.

2. What is represented by the gradient of a Force against Extension (F vs x) graph for a spring?

  1. Elastic Potential Energy
  2. Work Done
  3. Spring Constant (k)
  4. Acceleration due to gravity
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Answer: C

From F = kx, gradient ΔF/Δx = k (the spring constant).

3. Two forces of 6 N and 8 N act at a right angle (90°) to each other on a particle. What is the magnitude of the resultant force?

  1. 14 N
  2. 10 N
  3. 2 N
  4. 48 N
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Answer: B

Using Pythagoras' Theorem: F = √6² + 8² = √36 + 64 = √100 = 10 N.

4. An object resting on a smooth inclined plane at an angle θ to the horizontal accelerates down the slope. What is its acceleration?

  1. g cos θ
  2. g sin θ
  3. g / sin θ
  4. g tan θ
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Answer: B

The component of force parallel to the incline is F = mg sin θ. Using Newton's 2nd Law F = ma => ma = mg sin θ => a = g sin θ.

5. Two identical springs with spring constant k are connected in series. How does the extension of the series system compare to a single spring under the same load F?

  1. It is half the extension of a single spring.
  2. It is double the extension of a single spring.
  3. It is four times the extension of a single spring.
  4. It remains the same.
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Answer: B

In series, each spring experiences full load F and extends by x. Total extension xtotal = x + x = 2x (double).

6. A car of mass 1000 kg accelerates at 2.5 m s⁻² along a flat road. If resistive friction forces total 500 N, what driving force is produced by the engine?

  1. 2000 N
  2. 3000 N
  3. 2500 N
  4. 1500 N
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Answer: B

Resultant Force F = ma => F_engine - F_friction = 1000 × 2.5 => F_engine - 500 = 2500 => F_engine = 3000 N.

7. Which change increases the stiffness (spring constant k) of a steel helical spring?

  1. Increasing the length of the spring
  2. Using a wire with a smaller diameter
  3. Using a spring with a smaller coil diameter
  4. Replacing steel with copper
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Answer: C

A smaller coil diameter increases the stiffness and spring constant k of the spring.

8. When three coplanar forces act on a stationary object, what condition indicates that the object is in dynamic or static equilibrium?

  1. The forces are all parallel.
  2. The sum of the magnitudes of any two forces equals the third force.
  3. The forces form a closed vector triangle when arranged head-to-tail.
  4. The forces act at 120° relative to each other exclusively.
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Answer: C

If a body is in equilibrium under 3 forces, their vector sum is zero, which forms a closed head-to-tail triangle.

9. A stationary lamp of mass 2 kg is suspended by two light cables. What is the vector sum of all forces acting on the lamp?

  1. 19.62 N downwards
  2. 0 N
  3. 39.24 N upwards
  4. 9.81 N horizontally
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Answer: B

The lamp is stationary (in equilibrium), so the resultant force (vector sum of all forces) is 0 N.

10. A person of mass 60 kg stands on a weighing scale inside an elevator moving downwards with an acceleration of 2 m s⁻². Taking g = 9.81 m s⁻², what is the reading on the scale?

  1. 708.6 N
  2. 588.6 N
  3. 468.6 N
  4. 120.0 N
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Answer: C

When accelerating downwards, mg - R = ma => R = m(g - a) = 60(9.81 - 2) = 60(7.81) = 468.6 N.

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