A car of mass 1000 kg accelerates from rest to 20 m s⁻¹ in 5 s on a level road. The net horizontal force on the car is:
A2000 N
B4000 N
C5000 N
D10 000 N
Answer & Solution
Correct answer: B. 4000 N
1. Acceleration a = (v − u) / t = (20 − 0) / 5 = 4 m s⁻².
2. Net force F = m a = 1000 × 4 = 4000 N.
3. This net horizontal force comes from friction between tyres and road.
_Source: NCERT Class 11 Physics Ch 4 "Laws of Motion", §4.5 (worked-example methodology)_
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