10 questions · Form 5 Physics Bab 1: Force and Motion II
A picture frame of weight 12 N hangs vertically from a smooth nail using a string. The two segments of string make an angle of 60° with each other. What is the tension T in each segment of the string?
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. A picture frame of weight 12 N hangs vertically from a smooth nail using a string. The two segments of string make an angle of 60° with each other. What is the tension T in each segment of the string?
Answer: B
Vertical components support weight: 2T cos(30°) = 12 => 2T(0.866) = 12 => 1.732 T = 12 => T = 6.93 N.
2. What is represented by the gradient of a Force against Extension (F vs x) graph for a spring?
Answer: C
From F = kx, gradient ΔF/Δx = k (the spring constant).
3. 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)
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.
4. What happens when a spring is loaded beyond its elastic limit?
Answer: C
Exceeding the elastic limit leads to plastic deformation where the spring is permanently stretched.
5. 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?
Answer: B
Resultant Force F = ma => F_engine - F_friction = 1000 × 2.5 => F_engine - 500 = 2500 => F_engine = 3000 N.
6. An object resting on a smooth inclined plane at an angle θ to the horizontal accelerates down the slope. What is its acceleration?
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.
7. 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?
Answer: C
Horizontal component Fx = F cos(θ) = 50 × cos(30°) = 50 × 0.866 = 43.3 N.
8. When three coplanar forces act on a stationary object, what condition indicates that the object is in dynamic or static equilibrium?
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. 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?
Answer: B
In series, each spring experiences full load F and extends by x. Total extension xtotal = x + x = 2x (double).
10. 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?
Answer: B
Using Pythagoras' Theorem: F = √(6² + 8²) = √(36 + 64) = √100 = 10 N.