Physics Problem?? (Forces and Law of Motion)?

Question

We learned in class today and I just cant understand it when Im on my own but he still collects it before showing us how to do it so I guess I just need to ask on here...

1)... he did this by lifting and holding above his head a barbell whose mass was 253 kg. His mass at the time was roughly 113kg. Draw a free-body diagram and the forces in the problem. *Calculate the normal force exerted on each of his feet during the time he was holding the barbell.*

2)A gorillas mass is about 3.10x10^2 kg. Suppose it hangs from two vines, each of which makes an angle of 30 with vertical. Draw the diagram with forces and *find the magnitude of the force of tension in each vine. What would happen to the tensions if the upper ends of the vines were farther apart?*

Answer 1

1) He was in equilibrium when holding the barbell. So there must have been normal force at his feet equal to his and the barbell's weight. Weight is calculated from mass by
W = m*g. Remember that each foot will support half of the total weight.

2) Again there is equilibrium. The vertical components of the tension in both of the vines must add up to the gorilla's weight, W. The vertical component of tension in one vine:
Tv = T*cos30

So
Tv = W / 2

You can do the math.