I am in high school, taking a college Physics for Scientists and Engineers class. I am stuck on one problem concerning an atwood device.(adsbygoogle = window.adsbygoogle || []).push({});

I have an atwood device with two masses (m1<m2, m2 higher than m1, connected via a massless string) and a pulley with a mass Mp and radius Rp. The pulley rotates without friction about it's axis which is attached to the celing via a massless string.

There are 6 questions I need to answer about this device:

1. The magnitude of the acceleration of M2 is ..... that of m1.

2. T2 is ..... M2g.

3. The C.M. of Mp+M1+M2 does not accelerate.

4. m1g + M2g + Mpg is ..... T3.

5. T3 is ..... T1 + T2

6. T2 is ..... T1;

My choices are less than, greater than, equal, true, and false.

For #1, I'm pretty sure the accelerations are equal, ditto #6.

#2, m2g-T2=m2a, so T2=m2g-m2a, and is therefore less than m2g

#3, I thought the center of mass accelerates

#4, if the C.M. accelerates upward, T3 (the celing string) would be less, more if CM accelerates down, and equal if there is no acceleration.

(T3=M(system)*(a(system))+g))

#5, I'm really not sure how to relate T3 and T1 and T2, because I'm not sure if the CM accelerates.

If I could get help on whether or not the CM accelerates, I'm sure I could finish this, but right now I am stuck. Thank you.

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# Homework Help: Atwood Device

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