Classical Physics - Pulley Problem

[danny271828]

3 unknowns and only 2 eqs

 

[Dick]

You have expressions for the a's in terms of T and you can get expressions for the alpha's in terms of T. Put them both into a1+a2=r1*alpha1+r2*alpha2. All that's left is T. Solve for it. You aren't going in circles. You are just giving up. Don't be a weakling! It's ONE equation in ONE unknown.

 

[danny271828]

you still there? i don't really feel like I am getting anywhere... in fact i think I've been here before heh..

 

[Dick]

Yes, I'm still here. But I'm getting impatient. Solve this thing, ok?

 

[danny271828]

T = ((m1 + m2)G)/2

 

[Dick]

I'll get you started. You have already told me in so many words a1=g-T/m1 and alpha1=T/(m1*r1). Same for the 2's. Read back if you don't believe me.

 

[Dick]

T = ((m1 + m2)G)/2

You know that's wrong, right? How did you get that?

 

[danny271828]

ok heh got it...

 

[danny271828]

just been staring at this problem way too long...

 

[Dick]

You may thank me now. :)

 

[danny271828]

Thank you much for your infinite patience... I appreciate it :D

 

[Dick]

just been staring at this problem way too long...

You were missing the s'' thing. Conservation of string. If it's any comfort, I stared at it for a while myself.

 

[danny271828]

Yeh i should have stepped away from it for a while... after 3 hours or staring my brain went numb... thanks again man...