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awilhite
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Homework Statement
Ben does 600J of work pushing a 55kg cart 5m in the +x direction by applying a force at a downward angle of 30° to the direction of displacement. If the coefficient of kinetic friction μκ is equal to 0.1, find:
- The magnitude of the applied force.
- The work done by the force of friction on the cart.
Homework Equations
W = Fd
Work of friction = -μκ(mg + Fsinθ)d
Work in x direction = Fcosθ
The Attempt at a Solution
The magnitude of the applied force:
W = Fd
600 = F(5)
F = 120N
The work done by friction:
Wopp = -μκ(mg + Fsinθ)d
Wopp = -0.1(55*10 + 120sin30°)(5)
Wopp = -305J
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Is it right? I have an undying feeling that it is correct; however, the student teacher that teaches my class substituted the initial W = Fd with W = Fdcosθ. That would only give you the force in the x direction, and then the force of friction found in the second part would be incorrect, right?
Help me out, please. Thanks.