alleryUsing v² = u² + 2as, find the distance a car needs to stop from 20 m/s if its deceleration is 4 m/s²:
A100 m
B20 m
C10 m
D50 m
Answer & Solution
Correct answer: D. 50 m
v = 0 (stopping), u = 20 m/s, a = −4 m/s².
We have v² = u² + 2as → 0.
That is v² = 400 + 2(−4)s → 8s.
That is v² = 400 → s.
So v² = 50 m.
**So at 20 m/s, even with strong braking, you need 50 metres to stop.**
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