Massless strings/pulleys: Finding the magnitude of the Force

1. Oct 20, 2008

Graphire

1. The problem statement, all variables and given/known data
A massless string runs around two massless, frictionless pulleys, as shown in the figure below. An object with mass m = 10.3 kg hangs from one pulley. A force F is exerted on the free end of the string. What is the magnitude of the force F if the object is lifted at a constant speed?

2. Relevant equations
I'm guessing around 1/2m x v^2 but I really don't have a clue...

3. The attempt at a solution
Well so far I got that the force goes in the y axis so that he factors involving the y axis is the weight and tension. Since the question does not give me tension and I really don't know what formula to use to figure it out I'm quite lost.

There's also a diagram but I dunno how to put it up here...

2. Oct 20, 2008

Stovebolt

Can you try to describe the figure? Give the path of the string and position of the pulleys and mass, if you can.

Also, (1/2) m * v2 will give you units of work or energy. It sounds more like you need an equation dealing with force, mass, and acceleration.