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Question
A cyclist is travelling at 15 m s-1. She applies brakes so that she does not collide with a wall 18 m away. What deceleration must she have ?
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Solution
We have to find the deceleration. We have the following information given,
Initial velocity, (u) = 15 m/s
Final velocity, (v) = 0 m/s
Distance travelled, (s) = 18 m
Let the acceleration be (a)
We can calculate acceleration by using the 3rd equation of motion,
`a = (v^2 - u^2)/(2s)`
Put the values in above equation to find the deceleration,
a = (0-225)/(36)
⇒ `a =-6.25 "m/s"^2`
Thus , the deceleration is 6.25 `"m/s"^2`
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