Pulley problem, find total mass where ther is no acceleration

[vande060]

Homework Statement

you need to see the picture for this one

http://s861.photobucket.com/albums/ab174/alkaline262/?action=view&current=prob13.jpg

Homework Equations

f=ma

The Attempt at a Solution

i don't really know where to start on this one.

i have the equations for force

2T - m2g = -m2a2

N - m1g = 0

T = m1a1

i think i should set a to zero

2T = m2g
T=0

that step doesn't make sense to me, because how can the tension = 0 ?

 

[Liquidxlax]

are the pulleys negligible?

 

[vande060]

are the pulleys negligible?

yes they are

 

[vande060]

bump. i still don't understand this problem when i solve for t is get t = -2g/(1/m1 - 4/m2)

is that right? what can i do with it ?