Moving at 20 m/s , a remote controlled car of mass 1000kg hits a pile of sand and comes to rest in 10 s. Find the average force that acted to stop the car.

The same car now hits a wall and comes to rest in 1s. Find the average force that acted to stop the car.

Use knowledge gained from this problem to explain why airbags generally reduce injuried during a car crash.

Force*time=mass*changevelocity
a) [1000* -20 ]/10 = -2000
b) [1000* -20 ]/1 = -20000
c) Would Airbags reduce injuries because they are a lot softer than a steering wheel. They also allow more time for the head to hit the airbag which will reduce the force.

I'm not sure if I did the change of velocity part right but these are the answers I got and I was wonder if they are correct.

Yes, a, b, c are correct. However, you ought to put units in the answers. Numbers alone are meaningless.