A van travelling at 20 m/s brakes uniformly to rest in 8 s. What is its acceleration?
Answer and explanation
Correct answer: B. −2.5 m/s²
- Step 1: a = (v − u) ÷ t = (0 − 20) ÷ 8.
- Step 2: The result is −2.5 m/s², a deceleration.
Answer
−2.5 m/s².
Why not the others: 2.5 m/s²: the sign shows the van slows down. −160 m/s²: the speed was multiplied by the time. −0.4 m/s²: the time was divided by the speed.
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