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Quiz Chapter 1: Force and Motion II

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

Question 1 of 10Score: 0

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?

Full Question List & Answer Key

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1. 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).

2. A block of mass 5 kg rests on a frictionless 30° inclined plane. What magnitude of force applied parallel to the incline is required to keep it stationary? (g = 9.81 m s⁻²)

  1. 42.48 N
  2. 24.53 N
  3. 49.05 N
  4. 9.81 N
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Answer: B

Component of weight pulling down slope = mg sin(30°) = 5 × 9.81 × 0.5 = 24.525 N ≈ 24.53 N. An equal and opposite force maintains equilibrium.

3. 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.

4. 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.

5. 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.

6. A force of 50 N is applied to pull a box at an angle of 30° to the horizontal ground. What is the horizontal component of this force?

  1. 25.0 N
  2. 50.0 N
  3. 43.3 N
  4. 30.0 N
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Answer: C

Horizontal component Fx = F cos(θ) = 50 × cos(30°) = 50 × 0.866 = 43.3 N.

7. Two identical springs, each with a spring constant k = 200 N m⁻¹, are connected in parallel. What is the effective spring constant of the combined system?

  1. 100 N m⁻¹
  2. 400 N m⁻¹
  3. 200 N m⁻¹
  4. 50 N m⁻¹
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Answer: B

For parallel arrangements, keff = k1 + k2 = 200 + 200 = 400 N m⁻¹.

8. A boat is pulled along a canal by two ropes. Rope A exerts a force of 300 N at 20° north of east. Rope B exerts a force of 300 N at 20° south of east. What is the net force pulling the boat directly east?

  1. 563.8 N
  2. 600.0 N
  3. 205.2 N
  4. 300.0 N
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Answer: A

Vertical components cancel out (300 sin 20° = 300 sin 20°). Total horizontal force = 2 × 300 cos(20°) = 600 × 0.9397 = 563.8 N.

9. Why is it easier to pull a lawn mower than to push it across a rough lawn?

  1. Pulling reduces the horizontal resistance of air.
  2. Pulling increases the downward normal force.
  3. Pulling reduces the vertical downward component, decreasing effective weight and friction.
  4. Pulling increases the mass of the lawn mower.
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Answer: C

Pulling applies a force with an upward vertical component (F sin θ), reducing the net vertical reaction force R = W - F sin θ, which decreases friction.

10. 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
Show answer

Answer: C

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

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