Test: Force - Class 10 MCQ

Formula: F = m × a
Rearranged: a = F / m
Substitute: a = 20 / 5 = 4 m/s²
Conclusion: The acceleration produced is 4 m/s². A larger mass would reduce the acceleration for the same force.

Initial speed u = 20 m/s, final speed v = 0, time t = 5 s.
Acceleration a = (v - u) / t = (0 - 20) / 5 = -4 m/s² (negative means retardation).
Force F = m × a = 1000 × (-4) = -4000 N.
Magnitude of retarding force = 4000 N (direction: opposite to motion).

Momentum p = m × v
Rearranged: v = p / m
Substitute: v = 10000 / 2000 = 5 m/s
Conclusion: The truck's speed is 5 m/s.

F = m × a → m = F / a
m = 50 / 2 = 25 kg
Conclusion: The mass is 25 kg.

v = p / m = 80 / 20 = 4 m/s
Conclusion: Velocity = 4 m/s.

a = F / m = 30 / 10 = 3 m/s²
Conclusion: Acceleration = 3 m/s².

a = (v - u) / t = (0 - 4) / 2 = -2 m/s².
F = m × a = 2 × (-2) = -4 N. Magnitude = 4 N, direction opposite to motion.
Conclusion: Applied force (magnitude) = 4 N.

Change in momentum Δp = 20 - 40 = -20 kg·m/s.
Average force F = Δp / Δt = -20 / 5 = -4 N. Magnitude = 4 N.
Conclusion: Average force magnitude = 4 N, acting opposite to the initial motion.

m = F / a = 100 / 5 = 20 kg.
Conclusion: Mass = 20 kg.

Work W = Force × displacement = 10 × 2 = 20 J.
Conclusion: Work done = 20 J.

Centripetal force Fc = m × v² / r.
v² = 4 × 4 = 16. Fc = 2 × 16 / 1 = 32 N.
Conclusion: Centripetal force = 32 N toward the centre.

Moment = Force × perpendicular distance = 10 × 0.5 = 5 N·m.
Conclusion: Torque = 5 N·m.

For balance: anticlockwise moment = clockwise moment.
50 × 2.0 = 100 × d → 100 = 100 × d → d = 100 / 100 = 1.0 m.
Conclusion: The 100 N child must sit 1.0 m from the pivot.

Moment of couple = one force × separation = 20 × 0.4 = 8 N·m.
Conclusion: Couple moment = 8 N·m (it causes rotation only).

Initial velocity u = +10 m/s, final velocity v = -5 m/s (opposite direction).
Change in momentum Δp = m × (v - u) = 0.5 × (-5 - 10) = 0.5 × (-15) = -7.5 kg·m/s.
Average force F = Δp / Δt = -7.5 / 0.2 = -37.5 N. Magnitude = 37.5 N.
Conclusion: Average force magnitude = 37.5 N (direction: opposite to initial motion).

Weight W = m × g = 8.0 × 9.8 = 78.4 N.
Conclusion: Weight = 78.4 N.

Initial speed u = 0, final v = 20 m/s, t = 10 s. Acceleration a = (v - u) / t = 20 / 10 = 2 m/s².
Distance s = u×t + 0.5×a×t² = 0 + 0.5 × 2 × (10)² = 1 × 100 = 100 m.
Conclusion: The car covers 100 m.

Initial velocity u = 2 m/s, acceleration a = 3 m/s², time t = 4 s. Final velocity v = u + a×t = 2 + 3×4 = 14 m/s.
Momentum p = m × v = 4 × 14 = 56 kg·m/s.
Conclusion: Momentum after acceleration = 56 kg·m/s.

Centre of gravity is at 1.0 m from the end (midpoint). Moment = weight × distance = 100 × 1.0 = 100 N·m.
Conclusion: Moment about end = 100 N·m.

Centripetal acceleration ac = v² / r = 10² / 5 = 100 / 5 = 20 m/s².
Centripetal force Fc = m × ac = 3 × 20 = 60 N.
Conclusion: Centripetal force required = 60 N toward the centre.