Question

A car is travelling at speed of 30.0 m/s encounters an emergency and comes to a complete stop. how much time will it take for the car to stop it decelarates at -4.0 m/s2

Answer 1

To stop the car, the car would have a final velocity, v=0 m/s

We're going to use the first equation of motion i.e.

`\begin{gathered} v=u+at \\ 0=30+(-4)\cdot t \\ -30=-4t \\ t=-(30)/(4) \\ t=7.5\text{ s} \end{gathered}`

The car will need 7.5 seconds to stop.