Where does the force of tension act on a box?

[aspodkfpo]

Homework Statement

Where does the force of tension act on a box?

Relevant Equations

theta, phi

Given a force of tension with a string attached to the front of the box, do we take the force as acting with an angle to the centre of the mass of phi or theta? Explain please?

 

[haruspex]

Homework Statement:: Where does the force of tension act on a box?
Relevant Equations:: theta, phi

View attachment 268020
Given a force of tension with a string attached to the front of the box, do we take the force as acting with an angle to the centre of the mass of phi or theta? Explain please?

It acts at the point where it is attached, at the angle of the string.
If you are just looking at the balance of linear forces, (ΣF=ma) then the point of attachment is irrelevant, so you can take it as the centre of the block, but you must keep the angle actually applied.
When looking at torques, the line of action is important, so use the actual point of attachment, or any point in the same straight line as the string.

 

[aspodkfpo]

It acts at the point where it is attached, at the angle of the string.
If you are just looking at the balance of linear forces, (ΣF=ma) then the point of attachment is irrelevant, so you can take it as the centre of the block, but you must keep the angle actually applied.
When looking at torques, the line of action is important, so use the actual point of attachment, or any point in the same straight line as the string.

"angle actually applied" is theta right?

 

[haruspex]

"angle actually applied" is theta right?

Yes.