A car of mass 1000 kg is initially at rest. It moves along a straight road for 20 s and then comes to rest again. The velocity - time graph for the movement is given in figure 4. What is the magnitude of the net force that acts on the car while it is slowing down to stop from t = 15 s to t =20 s?
![996_fig.png](https://secure.tutorsglobe.com/CMSImages/996_fig.png)