A 1300 kg car is approaching the hill shown in at 11 m/s when it suddenly runs o

Question

A 1300 kg car is approaching the hill shown in at 11 m/s when it suddenly runs out of gas. Neglect any friction. Part A Can the car make il to the top of the hill by coasting? Yes, the car will pass the top of the hill and will continue to move down. Yes, the car will stop exactly on the top of the hill. No, the car will not read the top of the hill. More information is needed. Part B What is the car?s speed after coasting down the other side? Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

A) Required change in potential energy = mgh = 1300*9.8*5 = 63.7 kJ and the initial kinetic energy = (1/2)mv2 = 0.5*1300*121 = 78.65 kJ.

The initial kinetic energy is greater than the required change in potential energy so it will be able to the top of the hill.

B) The overall change in potential energy on the other side of the hill = -mgh = -1300*9.8*5 = -63.7 kJ.

So on the other side the car will be having kinetic energy = 63.7 kJ + 78.65 kJ = 142.35 kJ.

So the speed will be v = sqrt(2*KE/m) = 14.798 m/s

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