Question

a 25 kg rod has a box hanging from it and is suspended from the ceiling by the string. The entire system isin equilibrium. Calculate the tesnion in the string and calculate the mass of the box

Answer 1

This makes no sense: what is suspended from the ceiling? Is it vertical?

Answer 2

yes

Answer 3

Is the string massless? If the string is of mass per unit length p, then we will get tension as a function of height. However, if the string is massless, the tension in the string will simply equal the force that the box puts on it.
Draw a force diagram. That's how you always start mechanics problems.
So, the box is of mass m = 25kg, then the downward force due to gravity is F = mg = (25kg)(9.81m/s^2) = 245.25N. Therefore, by looking at our force diagram, we know that the tension, T, is equal to our force F. T = 245.25N