A car is on a freeway travelling at a high rate of speed. Suddenly, a dog runs i

frictional force fk = -uk*m*g from newtons second law force = m*a -uk*m*g = m*a a = -uk*g a = -0.37*32 = 11.84 ft/s2

ID: 1426638 • Letter: A

Question

A car is on a freeway travelling at a high rate of speed.

Suddenly, a dog runs in front of the car and the driver presses the brake pedal as hard as he can.

The anti-lock brake system (ABS) works perfectly, keeping the tires firmly in contact with the road as the car slows rapidly.

What is the car's rate of acceleration while it is slowing down, to the nearest 0.1 foot/second2?

Hints:

(1) You do not need to know the speed of the car, nor the mass of the car, to calculate the answer.

(2) Since the car is slowing down, the correct answer is a negative number.

frictional force fk = -uk*m*g

from newtons second law

force = m*a

-uk*m*g = m*a

a = -uk*g

a = -0.37*32 = 11.84 ft/s2

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