•a kid on a bike is at the top of a hill, at
rest. his ke = 0 j and gpe = 2500 j. he
rides down the hill and launches of a
ramp. during the jump, in the air, his gpe
= 1200 j. what is his ke at this time?

answer; /// i believe that the correct answer is (c)

none, its a machine

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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