Total kinetic energy for rolling hoop

In summary, the formula for calculating the total kinetic energy of a rolling hoop is K = 1/2 * I * ω^2 + 1/2 * M * v^2, where I is the moment of inertia, ω is the angular velocity, M is the mass, and v is the linear velocity. The moment of inertia affects the total kinetic energy by requiring more energy to rotate, resulting in a higher total kinetic energy. The total kinetic energy of a rolling hoop can change due to changes in mass, velocity, or surface. The linear velocity is directly proportional to the total kinetic energy, while the angular velocity is directly proportional to the square of the total kinetic energy.
  • #1
vetgirl1990
85
3

Homework Statement


A hoop has a mass of 200g and a radius of 25cm (ICM = MR2 ). It rolls without sliding along level ground at VCM = 5m/s. What is it's total kinetic energy?

Homework Equations


K = 1/2Iω2
ICM = MR2
v = rω

The Attempt at a Solution


The answer is 5J, but I'm getting 2.5J.

ICM = MR2 = (0.2)(0.25)(0.25) 0.0125
ω = v / r = 5/0.25 = 20

K = 1/2(0.0125)(20)2 = 2.5J

Am I omitting something from the total kinetic energy equation?
 
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  • #2
You should consider translational motion too.
 
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Likes vetgirl1990
  • #3
azizlwl said:
You should consider translational motion too.

Thanks! I forgot that a rolling object experiences both translational AND rotational motion. D'oh!
 

Related to Total kinetic energy for rolling hoop

1. What is the formula for calculating the total kinetic energy of a rolling hoop?

The formula for calculating the total kinetic energy of a rolling hoop is:
K = 1/2 * I * ω^2 + 1/2 * M * v^2, where K is the total kinetic energy, I is the moment of inertia of the hoop, ω is the angular velocity, M is the mass of the hoop, and v is the linear velocity.

2. How does the moment of inertia affect the total kinetic energy of a rolling hoop?

The moment of inertia, I, is a measure of an object's resistance to rotational motion. A larger moment of inertia means that the hoop will require more energy to rotate, resulting in a higher total kinetic energy.

3. Can the total kinetic energy of a rolling hoop change?

Yes, the total kinetic energy of a rolling hoop can change. It can change if the mass or velocity of the hoop changes, or if there is a change in the surface it is rolling on.

4. How does the linear velocity of a rolling hoop affect its total kinetic energy?

The linear velocity, v, of a rolling hoop is directly proportional to its total kinetic energy. This means that as the linear velocity increases, so does the total kinetic energy of the hoop.

5. What is the relationship between the total kinetic energy and the angular velocity of a rolling hoop?

The total kinetic energy, K, of a rolling hoop is directly proportional to the square of its angular velocity, ω. This means that as the angular velocity increases, the total kinetic energy of the hoop also increases at a faster rate.

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