Question

The brakes of a car are applied, causing it to slow down at a rate of 10 ft/s2. Knowing that the car stops in 300 ft, determine

Answer 1

Answer:

(a) The velocity of the car before the brakes were applied is 77.46 ft/s

(b) The time required for the car to stop is 7.8 s

Explanation:

Given;

acceleration of the car, a = 10 ft/s²

distance traveled by the car, d = 300 ft

(a) the velocity of the car before the brakes were applied is given;

v² = u² + 2ad

v² = 0 + 2(10 x 300)

v² = 6000

v = √6000

v = 77.46 ft/s

(b) the time required for the car to stop

d = ut + ¹/₂at²

d = 0 +  ¹/₂at²

d = ¹/₂at²

t² = 2d / a

t = √ ( 2d / a)

t = √ ( 2 x 300 / 10)

t = 7.8 s

Therefore, the time required for the car to stop is 7.8 s