A small, 250-μm-diameter bead is fired horizontally into 20∘C olive oil (η = 8.4×10−2Pa⋅s) at a speed of 0.29 m/s. Its stopping distance in the olive oil is 11 μm. What is the mass of the bead in μg? I'm not sure which equation I'm supposed to be using, or how to come up with one.

Two masses are connected by a rope that hangs over a pulley as shown below. the pulley is a uniform cylinder of radius 푅=0.381meters and mass 푀=3.1푘푔. initially 푚"is on the ground and 푚#rests 2.5 meters above the ground. if the system is released, use conservation of energy to determine the speed of 푚#just before it strikes the ground. assume the pulley bearing is frictionless.