AS Daily A Level Physics question
An e-scooter is braked so that its deceleration is constant until it comes to rest. If the rider starts at twice the original speed on the same stretch with identical braking, what happens to the stopping distance?
Answer
The correct answer is B.
Correct: B — It quadruples. A Halves — incorrect: higher initial speed cannot reduce stopping distance under the same deceleration. B — Correct because with constant deceleration the time to stop doubles when speed is doubled, so the area under the velocity–time graph (a triangle) scales as 1/2 × (2u) × (2t) = 4 times. C Doubles — incorrect: this assumes distance is proportional to speed only, ignoring that the stopping time also doubles. D Increases by a factor of three — incorrect magnitude; the distance scales with the square of the initial speed, not threefold.