Question

A car with an initial velocity of 60km/hr. is sprinting along a straight road, when the driver suddenly hit the breaks causing the car to skid on the road causing it to stop. The car leaves a 14.5m skid mark on the road. Compute for the total time it takes for the car to stop.

Answer 1

First, convert km/h to m/s by multiplying by 1000 and dividing by 3600. Then, recall that distance passed under uniformly accelerated (decelerated) motion from (to) zero velocity is

$$d=\frac{vt}{2},\rightarrow t=\frac{2d}{v}=1.74\text{ s}.$$