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

http://nplq1.phyast.pitt.edu/res/msu/physicslib/msuphysicslib/09_Force_and_Motion/graphics/prob69_2blkplly.gif

Two blocks are arranged as shown. The pulley can be considered to be massless, and friction is negligible. M1 is four times more massive than M2.

If the system is released from rest, how far will M1 travel in 0.809 s?

2. Relevant equations

F=ma

3. The attempt at a solution

Okay, basically I've tried multiple times to try and solve this and I keep getting it wrong...I'm not quite sure what else to try. I think I'm looking at the forces wrong somehow. When I input a wrong answer, I get the message "One force acts on the hanging mass, but the net force acts on both masses. Once you have the acceleration, you can calculate the distance." Wouldn't there be two forces, weight and tension?

My free body diagram for the mass on the table is its weight, its normal force, and its tension. It is four times more massive than the hanging mass, so T=4mg. For the hanging mass, I have only weight and tension. T-mg=ma. I tried solving for T in the second sum and plugging it into the first to find a, but I keep getting it wrong. I tried assuming that the mass of the hanging mass is added to the tension in the first, and that didn't work. Again, I assumed that M2=M and M1=4M. I assumed that the acceleration has to be the same for both blocks. To get the distance at the end, that would obviouslt be x=0.5st^2

ANY pointer or help would be greatly appreciated, thanks!

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: System of masses over a pulley

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