What work is required to stop the car in joules? If kinetic friction = .7, what is the stopping distance in m?

Question

A 1500 kg car is moving along a level road at 60 km/h

Answer 1

The kinetic energy of the car is

1/2 m v²

where m is the mass in kg and v the velocity in m / s. Convert 60 kph into m / s and calculate KE; that's also equal to the work required to stop the car.

If the coefficient of friction is .7 and the normal force is equal to the weight of the car mg, then the friction force is ( .7 ) mg. Work is force times distance, so set your energy from the first part equal to ( .7 ) mgd and solve for the stopping distance d.