I'm studying for a highschool physics midterm and I need some help here. The question involves 2 masses and a pulley.(adsbygoogle = window.adsbygoogle || []).push({});

A pulley of mas 3m and radius r is mounted on a frictionless bearing supported by a stand of mass 4m. I=(3/2)mr^2 Passing over the pulley is a massless cord supporting a block of mass m on the left and a block of mass 2m on the right. The cord does not slip.

A) Write the following

i. The equations of translational motion for each of the two blocks

ii. The analogous equation for the rotational motion of the pulley

Now, I have the answers, but I do not understand how collegeboard arrived at these answers, and I'm tired of pondering.

T(1)=tension in string over mass "m"

T(2)=tension in string over mass "2m"

i T(1) - mg = ma

2mg - T(2) = 2ma

ii I(alpha) = (T(2)-T(1))r

Can someone explain how these answers were arrived at?

Also, when 2 objects, of different mass, are hanging like this, the tension in the string is uniform, how can T(2) be different from T(1)?

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# Homework Help: Problem I must solve

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