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View Full Version : Physics, work energy theorems


leoman
Dec 1, 2013, 04:43 PM
A 450 kg car is driving at 60mph. The car hits a patch of ice and hits brakes. If coefficient of friction between tires and ice is 0.07, how far will the car slide before coming to a full stop. And how mechanical energy was taken by friction?

ebaines
Dec 6, 2013, 07:05 AM
Use equivalence of work and energy. The initial kinetic energy of thecar is:


KE = \frac 1 2 m v^2


This energy must be opposed by the work of friction that slows the car to zero. The work done by friction is:


W = Fd


You can calculate F given the car's weight and coefficient of friction. So now you have everything you need to calculate the distance. As for the second part of the question - I've already given you a good hint for that.