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A 3.00 kg block starts from rest and moves down a ramp on an incline of 30 degrees. If it makes it 2.00 m down the incline in 1.20 s, then:

a) what is the acceleration of the block?

This answer I got using dX=Vot + 1/2at^2. The answer is 1.78 m/s^2.

b) the coefficient of kinetic friction between the block and the ramp.

Here is where I run into problems. n can be found using mgcos30 (29.4cos30) which gives you n = 25.5. But I'm confused on how to determine the frictional force. I know it can't be -fk = ma, since the object is in moving so fk should be less than ma. How can I set this equation up? What variable am I not looking at? I know that uk = Fk/n, but how do I get Fk?

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# Homework Help: Coefficient of kinetic friction and acceleration

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