How Fast Will the Mass Be Just Before It Hits the Ground?

[benp]

Here is the problem, I've been trying for a day but can't seem to come up with the right answer.

A 4.0 kg mass is connected by a massless string over a massless and frictionless pulley to the center of an 8.0 kg wheel. Assume that the wheel has a radius of .5 m and a moment of inertia of 2.0 kg*m^2. The mass is released from rest at a height of 2.0 m above the ground. What will its speed be just before it strikes the ground? (Hint: Apply conservation of mechanical energy.)

Well, any help would be appreciated. I've tried cons. of mech. energy, but I come up with a wrong answer.

 

[enigma]

Hi benp,

Can you please post what you've done so far, so we can find where the mistake is?

Welcome to the forums.

 

[benp]

I'd love to but the stuff's in my car (which my sister's using right now). Ugh...if you only knew how long I've been working on this. It's getting late here now (almost 2am) but if you could help any I would apprecaite it very much.