2. . A record was set for stair climbing when a man ran up the 1500 steps of the

Question

2. . A record was set for stair climbing when a man ran up the 1500 steps of the Empire State Building in 11 minutes and 45 seconds. If the height gain of each step was 0.2 m, and the man's mass was 67.0 kg, what was his average power output during the climb?

1. The drawing shows a version of the loop-the-loop trick for a small car. If the car is given an initial speed of v = 3.0 m/s, what is the largest value that the radius rcan have if the car is to remain in contact with the circular track at all times? 6-41.gif 2. . A record was set for stair climbing when a man ran up the 1500 steps of the Empire State Building in 11 minutes and 45 seconds. If the height gain of each step was 0.2 m, and the man's mass was 67.0 kg, what was his average power output during the climb?

Explanation / Answer

1.What you really need is to make sure that the normal force (perpendicular force) exerted by the track on the car, never drops to zero.

To do that, make an equation for the normal force, as a function of the car's initial speed vi, and its position on the track.

Suppose the car has traveled through an angle ? around the track. At that point:

Its height is: h = r - rcos?.

its speed can be determined by conservation of energy:
?KE = ?PE
m(vi)

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