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fishfish
#1
Dec6-09, 07:37 PM
P: 20
1. The problem statement, all variables and given/known data

A block of steel is placed 120cm from the end of a sheet of metal. The sheet is raised just until the block begins to slide, which occurs when the block as 35cm above the surface of the table. the block is allowed to slide freely down the sheet until it slides onto the table. If the coefficient of friction is 0.20, what is the velocity of the block as it hits the table?

2. Relevant equations

Fxnet= Fg - Ff

Fynet= Fn + Fg = 0
Fn=Fg
Fn=mgcosθ

3. The attempt at a solution

Okay so I know that the angle would be 17 using trig.. But I don't exactly know how the masses cancel out here since we aren't given a mass. I know I have to find the acceleration of the block, and by finding that, I can find the final velocity using one of the five sisters. What I started out with was..

Fxnet = Fg + Ff
= mgsinθ + (Mu x Fn)
= mgsinθ + (Mu x mgcosθ)
= sin θ + (mu x cosθ) <--The thing is I'm not sure if I can do this or not..
=sin 17 + (0.2)(cos17)
= 0.1 N

then I don't know what to do after this..
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