Question

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.

Answer 1

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

Answer 2

thanks man!