A car accelerates uniformly from rest to 20 m s-1 in 8 s. The distance covered is
Correct answer: B. 80 m
- A. 40 m
- B. 80 m
- C. 160 m
- D. 320 m
Explanation
With uniform acceleration from rest the average velocity is half the final velocity, which is 10 m s-1, and over 8 s that gives 80 m. The same answer comes from finding a as 20 divided by 8, which is 2.5 m s-2, then using S equal to half a t squared. Using the final velocity of 20 m s-1 for the whole 8 s gives the wrong answer of 160 m.
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About Acceleration
Acceleration measures the rate at which velocity changes with time, including changes in speed, direction or both. Work includes average and instantaneous acceleration, the relation a = Δv/Δt, uniform acceleration equations, and interpreting velocity time and displacement time graphs, with acceleration carefully distinguished from velocity.
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