A driver with a 0.80-s reaction time applies the brakes, causing the car to have

Question

A driver with a 0.80-s reaction time applies the brakes, causing the car to have acceleration opposite the direction of motion. Assume the acceleration is equal to

-7.0 m/s2.

If the car is initially traveling at 25 m/s , how far does the car travel during the reaction time?

Express your answer to two significant figures and include the appropriate units.

How far does the car travel after the brakes are applied and while skidding to a stop?

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

Let the distance travelled during reaction time be s

s=ut+(1/2)at2

= (25*0.8)-(1/2)(7)(0.8)2

= 17.76m

The the distance the car travels after the brakes are applied be s

v2=u2+2as

0 = (252)-(2*7*s)

s = 44.64 m

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