You drive your 1,357-kg car at a constant speed of 23 mph down a ramp that has a

Question

You drive your 1,357-kg car at a constant speed of 23 mph down a ramp that has a grade of 15 %. Use conservation of energy to find the work done by the frictional force acting from the road on the tires. Define positive direction in the forward direction.



You drive your 1100-kg car at a constant speed of 23 mph down a ramp that has a grade of 17 %. Use conservation of energy to find the work done by the frictional force acting from the road on the tires. Then find an expression for the frictional force. Define positive direction in the forward direction. Check the correct answer.(Compare your result with what you found employing Newtons Law.)

fx = -mg sin 0
fx = mg sin 0
fx = -mg cos 0
fx = mg cos 0

Explanation / Answer

By conservation of energy = W.D by gravity + W.D by friction = 0 Let length of ramp = s Then, 0 = m*g*.17*s + W.D by friction We get, W.D by friction = -1100*9.8*.17*s =1832.6*s

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