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A box slides across a frictionless floor with an initial speed v = 2.8 m/s. It encounters a rough region where the coefficient of friction is µk = 0.7.

a) What is the shortest length of rough floor which will stop the box?

b) If instead the strip is only 0.28 m long, with what speed does the box leave the strip?

Relevant Equations:

Work Energy Theorem, Chane in Kinetic Energy = Work done on box.

I already found the answer to part a.)

(1/2)mv(final)^2 - (1/2)mv(initial)^2 = Ffriction

where i got: (1/2)(2.8)^2 = 0.7(9.81) * x

when i solved for x i got 0.571m

But its part b.) that i'm having the problem with. I set the problem up the same but solved for the velocity while i put in .28m for the distance

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Block on Floor with Friction

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