The skid marks from a car involved in an accident measured 73 feet. To the nearest tenth, what was the speed of the car before the brakes were applied?

speed of the car before the brakes were apply is 12.35 m/s

Explanation:

given data

accident measured distance = 73 feet = 22.25 m

to find out

speed of car before the brakes

solution

we consider here coefficient of kinetic friction between the road and the tires is 0.35

and we take speed of the car just before skidding = u

and final speed of car will be v = 0

now we apply here work energy theorem

so

0.5 mv² - 0.5 mu² = ( - coefficient of kinetic friction * mass * g) distance ... 1

0.5 (v² - u²) = ( - coefficient of kinetic friction * g) distance

put here value and we get

0.5 (0 - u²) = ( - 0.35 * 9.8) 22.25

solve it we get

u = 12.35

speed of the car before the brakes were apply is 12.35 m/s