physics
posted by brighton .
A gymnast weighing 72 kg hangs from a cross bar. His coach pushes him
forward with a force of 38 N and backward with a force of 20 N. The
upward reaction force on the gymnast is 750N. Calculate:
i). The resultant (net) force on the gymnast and
ii). The angle of the resultant force with the hands of the gymnast on
the cross bar. (15 marks)
(Show all the steps. W (Newton) = mg; where g is approximately 10 m/ S2

If they are going to try to teach you physics, I don't understand why they tell you to use the wrong value of g. It should be 9.81 m/s^2, on Earth.
Add the weight force (M*g) to the other three forces and compute the resultant. You have a total of 18 N backwards and 750 M*g up. If you used g = 10, that would be 30 N up.
The magnitude of the resultant is
sqrt[(18)^2 + (30)^2] = 34.99 N
The angle of the resultant arctan 18/30 or 31 degrees backwards from vertical.