Posted by **kiki** on Wednesday, November 30, 2011 at 9:14pm.

A 1400kg car starts at rest and rolls down a hill from a height of 12m. (a) how much kinetic energy does the car have at the bottom of the hill?(b) how fast is the car going at the bottom of the hill?

Can someone explain how to do it!

- physics -
**drwls**, Wednesday, November 30, 2011 at 11:17pm
They must expect you to neglect friction. The car would have to be in neutral gear, with well lubricated wheel bearings, and properly inflated tires.

The loss of potential energy, M g H, would then equal the gain in kinetic energy, (1/2)MV^2.

V = sqrt(2*g*H)

H = 12 m

g = 9.8 m/s^2

The car's mass does not matter when computing the velocity, but it does matter when computing kinetic energy. \

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