The Student Room Group

An object held by 3 strings atreached to a ceiling

72638434_2376420085915041_9184729503128092672_n.jpg
It’s a stupid question but why doesn’t mg=T3+T1sintheta+T2sinBeta ?

Suppose I understand why T1 and T2 are not acting on the mass

Having gotten the diagram on the right
I would’ve understood why T3=mg but our teacher gave us the diagram on the left. I understand why there are 2 T3’s in the string, if 2 ppl pull on a book, both will feel the forces, but
This is confusing me when it comes to deciding what forces act on the mass
If there’s a T3 force upwards in the string and another one downwards in the same string, don’t they cancel out the effects of each other
?
(edited 4 years ago)
You haven't posted a diagram ;-;
Reply 2
Original post by Callicious
You haven't posted a diagram ;-;

sorry, my fault.
There's the mg downward force and the tension upward force acting on the mass. Since the mass is not moving, then it is in equilibrium and T3=mg.
Nothing else is directly acting on the mass, therefore you ignore everything else in the diagram.

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