# Solid cylinder roll physics

• gamer1319
In summary, the problem involves a solid cylinder with a radius of 20 cm rolling down a 2.5 meter incline without losing energy to friction. The velocity and angular speed of the cylinder at the bottom of the incline can be found by using the equations I = mr^2 and E = mgh, and taking into account the rotational and translational kinetic energy. The mass of the cylinder is not necessary for solving the problem.

## Homework Statement

A solid cylinder of radius 20cm is released from a 2.5 high incline. If it rolls down without losing any energy to friction, find the cylinder's velocity at the bottom of the incline and the angular speed at the bottom of the incline.

## The Attempt at a Solution

I need to be given a mass to solve this! If I had a mass, I'd plug it into I = mr^2, find the inertia. With that, I'd plug it into E = mgh, and after i'd find W (angular velocity). Help!

Are you sure the masses don't cancel out? :)

gamer1319 said:

## Homework Statement

A solid cylinder of radius 20cm is released from a 2.5 high incline. If it rolls down without losing any energy to friction, find the cylinder's velocity at the bottom of the incline and the angular speed at the bottom of the incline.

## The Attempt at a Solution

I need to be given a mass to solve this! If I had a mass, I'd plug it into I = mr^2, find the inertia. With that, I'd plug it into E = mgh, and after i'd find W (angular velocity). Help!

The mass is m. You don't need to know the mass with this problem any more than you need to know the mass of an object to find its final speed after falling 2.5 meters, if it was released at rest.

Don't forget, the final Kinetic Energy, KE, includes a rotational part as well as a translational part, i.e. KE = (1/2)·I·ω2 + (1/2)·m·v2 .