h7p1 Suppose the ski patrol lowers a rescue sled and victim, having a total mass
ID: 2142836 • Letter: H
Question
h7p1
Suppose the ski patrol lowers a rescue sled and victim, having a total mass of 90.0 kg, down a ? = 70.0
Suppose the ski patrol lowers a rescue sled and victim, having a total mass of 90.0 kg, down a ? = 70.0 degree slope at constant speed, as shown in Figure 6.22. The coefficient of friction between the sled and the snow is 0.100. How much work is done by friction as the sled moves 30.0 m along the hill? How much work is done by the rope on the sled in this distance? What is the work done by gravity on the sled? What is the total work done?Explanation / Answer
T=mgsin(theta)-mu*mg*cos(theta)=90*9.8*(sin(70 degrees)-0.1*cos(70 degrees))=798 N
a) work is done by friction as the sled moves 30.0 m along the hill=mu*mg*cos(theta)*30=0.1*90*9.8*cos(70 degrees)*30=-905 J
b) work is done by the rope on the sled in this distance=798*30=-23940J
c) work done by gravity on the sled=90*9.8*sin(70 degrees)*30=+24860 J
d) total work=0 J
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