Posted by eddy on .
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.

College Physics 
bobpursley,
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 KEFinalKE=Force*distance
1/2 mvi^21/2mvf^2=Force*130
solve for force.