Use the worked example above to help you solve this problem. An Eskimo returning
ID: 1660893 • Letter: U
Question
Use the worked example above to help you solve this problem. An Eskimo returning from a successful fishing trip pulls a sled loaded with salmon. The total mass of the sled and salmon is 50.0 kg, and the Eskimo exerts a force on the sled by pulling on the rope. Suppose the coefficient of kinetic friction between the loaded sled and snow is 0.200. (a) The Eskimo pulls the sled 5.70 m, exerting a force of 1.10 102 N at an angle of = 0°. Find the work done on the sled by friction, and the net work.
Wfric =
J Wnet =
(b) Repeat the calculation if the applied force is exerted at an angle of = 30.0° with the horizontal.
Wfric =
Wnet =
Explanation / Answer
a) work done against friction
Wf = u m g S
= 0.2 x50 x9.8 x5.7
= 558.6 J
ner work done
Wnet = F S - Wf
= 110 x5.7 - 558.6
= 627 - 558.6
= 68.4 J
b) now the normal reaction will change so, the friction force will also change
Wf = u (m g-Fsin30) S
= 0.2[(50*9.8)-(110sin30)]5.7 J
=495.9
net work done
Wnet = FS cos(30) - Wf
= 110 x 5.7 x0.866 - 495.9
=47.082J
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