October 22nd, 2016, 07:22 AM  #1 
Member Joined: May 2016 From: Ireland Posts: 96 Thanks: 1  pulley system
a light inextensible string passes over a fixed pulley A, under a movable pulley B of mass M and then over a second fixed pulley C. A mass m is attached to one end of the string and a mass 3m is attached to the other end. the system is released from rest. (i) prove that the tension t in the string is given by the equation t(1/m + 1/3m)=g (g stands for gravity) i cant prove this even though i feel like i am doing all the the right equations. the 3 equations i get by using f=ma and looking at all the particles seperately are tmg=ma t3mg=3mb Mg2t=M(a/2 + b/2) a stands for the acceleration the particle of mass m. b stands for the acceleration of the particle of mass 3m. a/2 + b/2 stands for the acceleration . when i get a and b on there own from the first 2 equations and put this in for a and b in the last equation i do not get the answer required. i can post a picture of the diagram in the question if anyone needs it. any help much appreciated


Tags 
pulley, system 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Using Newton's laws etc. pulley type.  devour19  Applied Math  9  March 22nd, 2016 03:34 PM 
Very Simple Pulley Question  bitsnbitting  Physics  1  February 3rd, 2014 09:01 PM 
Pulley / Inclined Plane Physics Question  Lones  Physics  6  November 14th, 2010 06:39 PM 
HELP !! Masses on inclined plane with pulley and friction !!  GBR1026  Applied Math  0  December 31st, 1969 04:00 PM 