# Looking for good websites to learn physics

Discussion in 'MCAT Discussions' started by ftcnt, Apr 30, 2007.

1. ### ftcnt Junior Member

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I'm studying the physics section and im using the EK1001 questions. I'm stumbling on the tension and force questions and wondering if people could provide some helpful links and resources to understand these concepts. I want to be able to understand the concepts and trying really hard not to just memorize.

thanks

3. ### cheezer Guest

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don't know any

just know that force problems essentially involve the summation of forces in the x component and the summation of the forces of the y component set equal to either 0 or ma (if the mass is accelerating). draw free body diagrams and Fx and Fy equations for every single mass in the system then solve for the unknowns. no need to memorize.

4. ### studiddy

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Just out of curiosity, can you just always set it to equal zero, and then just add ma to one side, and then if it looks wrong just assume you added it to the wrong side?

5. ### cheezer Guest

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don't go by "looks wrong." You have to pay attention to whether it's moving or not and what direction it's moving in. But to answer your question, yes, you can bring everything over to one side and set it equal to zero if you like. So something like,

T-mg=ma
and
T-mg-ma=0

is the same thing. I personally don't do it this way though. I sum up the forces and then if it moves, i set it equal to ma. if it doesn't, i set it equal to 0. This is so I don't get confused as to whether the object is moving or not. Of course on the other hand, you can tell that the object is accelerating downward with the other one, so i guess it doesn't really matter. Just pay attention to signs. T-mg+ma=0 obviously tells a different story