# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## JDK1.0.2 simulations (1996-2001) => Dynamics => Topic started by: Bitupon on December 14, 2005, 03:56:15 pm

 Title: Another Pulley Problem Post by: Bitupon on December 14, 2005, 03:56:15 pm [size=18:825bcc8bd7][b:825bcc8bd7]Two blocks A and B of mass 1kg and 2kg respectively are connected by a string, passing over a light frictionless pulley. Both the blocks are resting on a horizontal floor and the pulley is held such that string remains just taut. At moment t=0 ,a force F=20t N starts acting on the pulley along vertically upward direction as shown in the figure. Calculate(a) Velocity of A and B when loses contact with the floor.(b) Height raised by the pulley upto that instant and(c) Work done by the force upto that instant(Consider g=10m per sec sq.)[/b:825bcc8bd7] [/size:825bcc8bd7](http://img208.imageshack.us/img208/2625/slaws0sj.jpg)[size=24:825bcc8bd7][color=red:825bcc8bd7]Solution:(a) Let T be the tension in the string .2T=20tOr, T=10t NLet the block A loses its contact with the floor at time t=t¡¦.This happens when the tension in the string becomes equal to the weight of A.Thus,T=mgOr,10t¡¦=10Or, t¡¦=1secSimilarly for block B,we have10 t¡¦¡¦=20Or, t¡¦¡¦=2seci.e. the block B loses contact after 2secs.For block A , at time t such that t¡¦