Question

A 1200 kg automobile travels at 9 m/s.  

1. What is its kinetic energy? 
2. What net work would be required to bring it to a stop? 

Answer 1

Given:

$m=1200\:\rm kg$

$v=9\:\rm m/s$

1)

$$E_k=\frac{mv^2}{2}=\frac{1200*9^2}{2}=48600\:\rm J$$

2)

$$W=-\Delta E_k=-48600\:\rm J$$