What is the mechanical advantage of a pulley system that uses 280 N to lift a 320 Kg box 4.0 m in the air?

the force of effort is given as

E = effort force = 280 N

m = mass of box to be lifted = 320 kg

g = acceleration due to gravity = 9.8 m/s²

force of load due to weight of box is given as

L = force of load = mg

L = 320 x 9.8

L = 3136 N

mechanical advantage for pulley system is the simply the ratio of the effort put in to the load being lifted.

mechanical advantage is given as

MA = load/effort

MA = L/E

MA = 3136/280

MA = 11.2