Pulley

figure
A force is exerted directly up on the axle of a pulley. Consider the
pulley and string to be massless and the pulley has no friction. Two
objects: m_{1} with mass 1.2 kg and m_{2} with mass 1.9 kg are
attached to the opposite ends of the string which passes over the
pulley. The object m_{2} is in contact with the floor.

a) What is the largest value the force \vec{F} may have so that
m_{2} will remain at rest on the floor?

b) What is the tension in the string if the upward force F is 110 N?

c) With the tension found in part b, what is the acceleration of m_{1}?