posted by Sean on .
A cord passes over a weightless and frictionless pulley. Masses of 200 g and 300 g are attached to the ends of the cord. Find the distance the masses will move during the 5th second after they are started from rest.
This is called an Atwood's machine and the acceleration rate is
a = [(M2 - M1)/(M1 + M2)]*g
M2 (the 300 g mass) goes down while M1 (200 g)goes up at this acceleration rate.
a = g/5
Distance moved t seconds after starting = (a/2) t^2
Distance moved from t= 4 to t=5 seconds is:
= (a/2)(5^2 - 4^2)
= (g/10)(25 - 16)
= 8.82 m