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Gold3nlily
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Homework Statement
A 230 kg crate hangs from the end of a rope of length L = 12.0 m. You push horizontally on the crate with a varying force to move it distance d = 4.00 m to the side (Fig. 7-43). (a) What is the magnitude of when the crate is in this final position?
Figure:
http://edugen.wiley.com/edugen/courses/crs4957/halliday9118/halliday9118c07/image_n/nt0043-y.gif
(This is just a problem from the back, not homework...)
Homework Equations
W = F*d
W = KEf - KEi
(I'm supposed to solve this without using conservation of energy (that is next chapter), only work, forces, and kinetic energies)
The Attempt at a Solution
Normally I would set the two equations equal to each other, but I don't know either velocity and I cannot find a way to cancel them out of the equation.
I also have a question about the angle between the force and the distance. When I look at the picture it looks like the force is horizontal, but the displacement of the box itself is kind of slanted upwards. I am i supposed to ignore that (the arrow indicating the displacement below the box is horizontal)?
Then about the forces, i think that the tension force and the gravitational force does no work becasue it is perpendicular to the displacement, is this right?
I also found the angle at the top of the figure:
@ = tan^-1 (4m/12m) = 18.435 degrees
I feel a little stuck right now. Could anyone please give me a kick start? Is there an equation I am neglecting? Is there a way to solve this problem without using conservation of energy?
Oh and the answer from the book is: 797 N
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