Question

A driver in a car traveling at a speed of 21.8 m/s sees a cat 101 m away on the road. How long will it take for the car to accelerate uniformly to a stop in exactly 99 m?

Answer 1

Answer:

t = 9.08 sec

Explanation :

This requires the use of the kinematic equations.

u = initial velocity = 21.8 m/s

v = final velocity = 0

t = time = what we're trying to find.

So we use the equation that relates d, u, v and t. This is

d = distance = 99m

d = $\frac{t*(u+v)}{2}$

and since v = 0 this reduces to d = $\frac{tu}{2}$

which rearranges to t = $\frac{2d}{u}$

t = $\frac{2*99}{21.8}$ =9.08 seconds

t = 9.08 sec