A skateboarder is practicing on the \"half-pipe\" that has a height of 4 meters,

Question

A skateboarder is practicing on the "half-pipe" that has a height of 4 meters, using a special frictionless skateboard. (You can also ignore the kinetic energy of the skateboard's wheels.) (a) If she starts from rest at the top of the half-pipe, what is her speed at the bottom? (b) If the skateboarder has mass (m = 40 kg), what is her apparent weight at the bottom of the half-pipe? (c) What speed does she then have when she reaches the top edge on the other side of the half-pipe? (d) Now suppose she has a speed of 14 m/s at the bottom of the half-pipe. What is the highest point she can reach? Hint: This point may be above the edge of the half-pipe. (Enter the distance from the bottom of the half-pipe.) m

Explanation / Answer

a) potentail energy=mgh= 40*9.81*4=1569.6J

Kinetic energy=potential energy= 1/2mv2 =1596.6

slving for v

v=8.934 m/s

b) apparent weight= mg=9.81*40=392.4 N

c) Her speed will appraoch to zero as kinetic energy is converted to potential energy

d) kinetic energy=1/2mv2 =1/2*40*142=3920J

at the top kinetic energy is equal to potential energy=mgh=3920

solving for h

h= 9.989m

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