Question

The driver of a car traveling at 60 ft/sec suddenly applies the brakes. The position of the car is s(t) = 50t - 2t2, t seconds after the driver applies the brakes. How many seconds after the driver applies the brakes does the car come to a stop? (4 points)

Answer 1

t=12.5s

Explanation:

s(t) = 50t - 2t^2

v(t) = 50 - 4t

a(t) = -4

When v(t) = 0, the car stops.

v = u +at

0 = 50 + (-4)t

t = 12.5