the driver of a 1200 kg car notices that the car slows from 20 m/s to 15 m/s as it coasts a distance of 130 m along level ground. how large a force opposes the motion? (book answer .81 kN )

Question

the driver of a 1200 kg car notices that the car slows from 20 m/s to 15 m/s as it coasts a distance of 130 m along level ground.  how large a force opposes the motion?  (book answer .81 kN )
can you help me plug the numbers into the correct formula to use for this question.

bobpursley · Answer

College physics is not about plugging numbers into the correct formula. It is about analyzing, and using a math model to predict an outcome.

Here energy comes to mind. Some force over some distance is absorbing kinetic energy from the car.

Intial KE-FinalKE=Force*distance
1/2 mvi^2-1/2mvf^2=Force*130
solve for force.

Anonymous · Answer

.81