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Homework Statement
I have a few questions I need help with on my assignment. I cannot wrap my head around this work and energy chapter.
Anyway here it is;
A 62.7-kg skier coasts up a snow-covered hill that makes an angle of 25.2° with the horizontal. The initial speed of the skier is 8.22 m/s. After coasting 2.09 m up the slope, the skier has a speed of 3.20 m/s. Calculate the work done by the kinetic frictional force that acts on the skis
Homework Equations
W=Fd
Wtotal=1/2mvf^2-1/2mvi^2
The Attempt at a Solution
FBD. Fn in the positive y-direction, mgcos(theta) in the negative y-direction, Fk and mgsin(theta) in the negative y-diretion.
WFN=0 ----> makes a 90deg angle with the direction.
Wmgcos(theta)=0
Wmgsin(theta)=Fd
=(mgsin25.2)(2.09m)
=(62.7kg)(9.8m/s^2)(0.426)(2.09m)
=548J
WFk= ?
WTOT= 0+0+548+WFk = 1/2mVf^2-1/2mVi^2
=> 548J+WFk=321J-2120J
=> WFk=-1800J-548J=-2350J
I am using three sig digits for my calculations. The answer is wrong.