1. As a snowboarder descends a mountain slope, gravity, the normal force, and fr
ID: 2038064 • Letter: 1
Question
1. As a snowboarder descends a mountain slope, gravity, the normal force, and friction combine to exert a net force of 320N in the downhill direction. The net force does 4700J of work on her during one segment of her descent. Her path cuts across the face of the mountain at a 65.0° angle from the direction of the net force. (I) (10 points) Over what distance does she travel? (II) (10 points) By how much did her kinetic energy change during this segment? (III) (10 points) If her mass is 65.3kg and her speed at the begining of the segment was 8.00 m/s, what's her final speed after finishing the segment?Explanation / Answer
1) Net workdone, Wnet = Fnet*d
d = Wnet/Fnet
= 4700/320
= 14.7 m
2) using work-Energy theorem,
change in kinetic energy = Wnet
= 4700 J
3) using work-energy theorem,
Wnet = delta_KE
Wnet = (1/2)*m*(vf^2 - vi^2)
2*Wnet/m = vf^2 - vi^2
==> vf = sqrt(vi^2 + 2*Wnet/m)
= sqrt(8^2 + 2*4700/65.3)
= 14.4 m/s
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