Posted by **Goldberg** on Saturday, May 5, 2012 at 9:07pm.

One end of the string in the diagram at right is wrapped around the cylinder. The other end is tied to the ceiling. The cylinder is released from rest. How fast is it moving after it falls 3.0m?

- Physics 121 -
**Goldberg**, Saturday, May 5, 2012 at 9:08pm
Please show the formula and how you do it. Thx

- Physics 121 -
**bobpursley**, Saturday, May 5, 2012 at 9:13pm
Look at energy:

potential energy lost= kinetic energy gained

mgh=1/2 m vf^2 +1/2 I w^2

mgh=1/2 m vf^2 + 1/2 I (vf/r)^2

Now, you have to decide the moment of inertia for the cylinder. Solid, or not. Lets just assume it is hollow for this demonstration.

I= m r^2

then

mgh= 1/2 m vf^2+1/2 m vf^2

Now, average velocity going down was Vf/2, so in three seconds it went 1.5Vf

h= 1.5Vf

1.5 mg Vf= 1/2 m Vf^2+ 1/2 m Vf^2

you can solve for Vf.

I would divide by mVf, and solve

## Answer This Question

## Related Questions

- Physics - A massless string is wrapped around a cylinder of mass 0.400 kg and ...
- physcs - A string is wrapped around a uniform solid cylinder of radius 3.10 cm, ...
- Physics - Consider a stainless steel annular disk with an outer radius 68mm and ...
- Physics - Consider a stainless steel annular disk with an outer radius 68mm and ...
- physics - A string is wrapped around a uniform solid cylinder of radius r. The ...
- Physics - Consider a stainless steel annular disk with an outer radius 66 mm and...
- physics incline - A cord connected at one end to a block which can slide on an ...
- physics - A long string is wrapped around a 6.2cm diameter cylinder, initially ...
- phsyics - A long string is wrapped around a 6.4-cm-diameter cylinder, initially ...
- physics - A light inflexible cable is wrapped around a cylinder of mass , radius...

More Related Questions