1. Homework Statement
problem is above
sum of torques = I * angular acceleration = 0 for rotational equilibrium
The Attempt at a Solution
OK, here's what I tried to do.
I wrote sigma Fy = Fleft pier up + F secondleftpierup - Fg,beam = 0
I assumed that the two piers have equal forces, so then I said that
2 * Fsinglepier = Fg,beam
2 * Fsinglepier = 100 kg * 9.8 m/sec^2.
Fsinglepier = 50 * 9.8.
Then I did my rotational equilibrium equation, and I assumed that there was no man in the pier initially. My axis of rotation is at the very left end of the pier:
sum torques = +Fsecondpier [which is 50 * 9.8] * 3 meters - [ 100 kg * 9.8 * 5 meters] (for the center of mass of sphere and the force of gravity acting through it
which gives = -3430 N-m.
This obviously implies that the system is already experiencing a net torque without the man, so the man can not even be on the system to balance it out in any fashion.
The solutions [which might be wrong, due to crummy question authors] say that 3 is the answer without providing any other guidance. Please help, and thanks in advance!