posted by Mikaela .
A cord runs around two massless, frictionless pulleys; a canister with mass m=20 kg hangs from one pulley; and you exert a force F if you are to lift the cord.
a) What must be the magnitude of F if you are to lift the canister at a constant speed?
b) To lift the canister by 2 cm, how far must you pull the free end of the cord? During that lift, what is the work done on the canister by c) your force (via the cord) and d) the gravitational force on the canister?
I don't get the picture. What is the second pulley doing?