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i have two 2D vector problems here that i'm stuck on! help is appreciated!

1) A boy sits at the top of a slide. When the slide makes an angle of 35.0 degrees with the horizontal, the boy is just on the verge of slipping. If the boy starts to move down the slide, the slide angle can be reduced to 33.0 degrees and the boy is then able to descend the slope at 2.00m/s. Find µk and µs. (the answers, respectively, are 0.649 and 0.700)

I've drawn diagrams of the problem already, but what i'm stuck on is just how to calculate µs and µk. all of the formulas that i am aware of calculating these use mass. ie) µk= Ff/Fn. what sort of ways can i execute this problem without using mass????

2) A 45.4kg box is placed at the top of an incline (µs = 0.500, µk= 0.400) will the box move? If it does, what is its speed at the bottom of the incline? (the answer is 4.25m/s)

i'm not sure, but i'm thinking that there will have to be an acceleration greater than 9.81m/s^2 inorder to move. i have a diagram here in which a 45.4kg box is placed on an incline at 30.0 degrees to the horizontal and is 3.00m high. :yuck:

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# Homework Help: More 2D Vector Problems GAK!

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