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snoopyrawr
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Homework Statement
i've been stuck on this problem for about 45mins.
A constant external force P = 160 N is applied to a 20 kg box,which is on a rough horizontal surface. The force pushes the box a distance of 8.0 m, in a time interval of 4.0 s, and the speed changes from v1 = 0.5 m/s to v2 = 2.6 m/s. Find the work done by friction. The work done by friction is closed to:
There is a force applied at 30degree to the horizontal of the box.
the answer is -1043 J but idk how to get that answer.
Homework Equations
Ff = µFn
W=Fd
W=mgd
The Attempt at a Solution
W=mgd
W=20kg*9.8*cos(30)*8=1357.9J
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