(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

There is a table with a 6.9 kg box and a 5 kg box on it, connected by a string. The string goes around a pulley on the corner of the table, between the 5 kg box and a 35 kg box which it holds up. The coefficient of friction is .55 b/w the table and 6.9 kg box and .33 b/w table and 5 kg box. After releasing the system from rest, the 35 kg box descends .2 m. I need to find the speed of the 35 kg mass and the time it takes to drop .2 m.

2. Relevant equations

more work-energy

3. The attempt at a solution

I solved the first part of the question, which asked for the work done against friction. The answer is 10.6722 J. In my attempt at speed, I took the potential energy of the mass (35 x 9.8 x .2), subtracted the work done against friction, and set the answer equal to the kinetic energy at the end, but the resulting velocity was wrong. I'm sure I can just use kinematics to find time once I get the final velocity?

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# One more: three block, a table, and a pulley

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