posted by kj .
Two crates are connected by a massless rope that passes over a pulley as shown in the figure below. If the crates have mass 32 kg and 80 kg, find their acceleration. If the system begins at rest, with the more massive crate a distance 11 m above the floor, how long does it take for the more massive crate to reach the floor? Assume the pulley is massless and frictionless.
total mass that must be accelerated = 112 kg
Total force doing the accelerating = 80*9.8 N = 784 N
a = F/m = 784/112
= 7 m/s^2
d = 11 = (1/2) a t^2
22 = 7 t^2
t = 1.8 seconds