text: a 24 kg mass and a 13 kg mass? are suspended by a pulley with a radius of 4.9 cm and mass of 6 kg.  cord is negligible in mass, pulley rotates witout slipping or friction.  the masses start from rest 4 m apart (on is higher than the other), the pulley is a uniform disk.  acceleration of gravity = 9.8 m/s^2.  calculate the speeds of the two masses as they pass each other in units of m/s. f=ma.  let t= tension in the cord.  for 24kg mass:  f=24g-t 24g-t=24a t=24g-24a  for 13kg mass:  f=t-13g t-13g=13a  substitute value of t for 24kg mass:  24g-24a-13g=13a 37a=11g a=11g/37   =2.91m/s^2  compute time t:  s=ut+1/2at^2  for 24kg mass, s=x  x=0+1/2*2.91t^2  for 13kg mass, s=4-x  4-x=0+1/2*2.91t^2  substitute value of s for 24kg mass:  4-1/2*2.91t^2=1/2*2.91t^2 2.91t^2=4 t^2=4/2.91 t=1.17s  speed v of 24kg mass is equal to speed of 13kg mass  v=u+at  v=0+2.91*1.17 v=3.4m/s  the assumptions here are that tension t in cord for 24kg mass equals that for 13kg mass, acceleration of 24kg mass equals that of 13kg mass, and v of 24kg mass equals v of 13kg mass. the 24kg mass and 13kg mass meet at point x from 24kg mass, and at 4-x from 13kg mass.