Question

A car moving along a straight highway with speed of 126kmh is brought to stop within a distance of 200m l. Find the necessary retardation of the car and time for to stop it.

Answer 1

Retardation is nothing but acceleration in a opposite direction.

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u = 126 km/h = 35m/s

v = 0

s = 200m

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Using the formula

v²-u² = 2as

we get

0² - 35² = 2×200×a

-1225 = 400a

a = -1225/400

a = -3.0625 ms^-2

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To find time

v = u + at

0 = 35 + -3.0625×t

t = 11.42s

Answer 2

check the attachment

hope it helps