Question

Ann is driving down a street at 64 km/h. Suddenly a child runs into the street. If it takes Ann 0.747 s to react and apply the brakes, how far will she have moved before she begins to slow down?

Answer 1

13.3 m

Step-by-step explanation:

During the reaction time of Ann, her velocity is constant, so the distance travelled during that time is given by

`d=vt`

where

v is the velocity

t is the reaction time

First of all, let's convert the velocity from km/h to m/s:

`v=64 km/h \cdot (1000 m/km)/(3600 s/h)=17.8 m/s`

The reaction time is

t = 0.747 s

So, the distance covered during this interval is

`d=(17.8)(0.747)=13.3 m`