# Homework Help: Help on a pulley problem

1. Sep 8, 2009

### unicycle456

1. The problem statement, all variables and given/known data
A pulley is used in an experiment. A small block is attached to a string, the other end of which is attached to a pulley and wrapped around it several times. The block is released from rest and takes time t to fall the distance D to the floor. Using quantities given in the problem, express a formula that could be used to calculate the acceleration of the block.

2. Relevant equations
v1=v0 + at? v1= v0 + gt?

3. The attempt at a solution
i tried to put that into terms of a
a=(v0+t)/v1 but i know that i am way off because there is nothing about distance in there and just seems wrong. i am also confused, is this a freely falling object or not because the rope is wound around the pulley.

Last edited: Sep 8, 2009
2. Sep 8, 2009

### semc

Maybe you want to consider X1=Xo+vt+1/2at^2 where X1 = D. Since it is released from a certain point, you should know what the initial velocity is.Alternatively you can consider conservation of energy.