A car traveling at 72 km/hr hits a tree. the driver, who has a mass of 55.0 kg comes to a rest 0.10s after the impact.

Question

What is the force that acts on the driver?

Answer 1

72 km/hr = 20 m/s
So, the deceleration is (20m/s)/(.1s) = 200m/s^2

Now the force F=ma, so ...

Answer 2

I would solve it this way:
force*time=mass*changeinvelocity

Answer 3

8980