What is the magnitude of tension in the string supporting the pulley

[bulbasaur88]

If mass 1 is 5 kg, and mass 2 is 3 kg, what is the magnitude of tension in the string supporting the pulley, T1?

The answer is 74 N.

What I presume they did was to find tension in the string and then double that to get ~74 Newtons.

My question is: why isn't T1 simply the weight of the two blocks?

 

[PhanthomJay]

View attachment 38050

If mass 1 is 5 kg, and mass 2 is 3 kg, what is the magnitude of tension in the string supporting the pulley, T1?

The answer is 74 N.

What I presume they did was to find tension in the string and then double that to get ~74 Newtons.

Yes, using a FBD of the pulley in equilibrium.

My question is: why isn't T1 simply the weight of the two blocks?

It would be if the system was in equilibrium. Is it??

 

[bulbasaur88]

O.k. I think I see what you are saying. Thank you