Kinetic Energy of Rotating+Translating Bar

In summary, when a cart with a rotating bar attached to its center moves in the x-direction, the kinetic energy of the bar can be calculated using the formula KE=\frac{1}{2}m\vec{v}_{C.M}^{2}+\frac{1}{2}\vec{\omega}\cdot\vec{L}_{C.M}, where m is the mass of the object, \vec{v}_{C.M} is the velocity of the center of mass, \vec{\omega} is the rotational velocity of the object, and \vec{L}_{C.M} is the angular momentum of the object computed relative to the center of mass.
  • #1
enkar
7
0
If a cart is moving in the x-direction and has a bar (not a pedulum) attached to its center that will rotate, what are the terms of the kinetic energy? I'm having a hard time figuring out what the kinetic engery of the rotating+translating bar is. Can someone break it all down into each of the terms, please?
 
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  • #2
Since the bar is a rigid object(?), its kinetic energy may be written as:
[tex]KE=\frac{1}{2}m\vec{v}_{C.M}^{2}+\frac{1}{2}\vec{\omega}\cdot\vec{L}_{C.M}[/tex]

Here, we have:
m-object's mass
[tex]\vec{v}_{C.M}[/tex]-velocity of center of mass (C.M)
[tex]\vec{\omega}[/tex]-rotational velocity of object
[tex]\vec{L}_{C.M}[/tex]-angular momentum of object, computed relative yo C.M
 

1. What is the equation for calculating the kinetic energy of a rotating and translating bar?

The equation for calculating the kinetic energy of a rotating and translating bar is E = 1/2 * (m * v^2 + I * ω^2), where E is the kinetic energy, m is the mass of the bar, v is the linear velocity, I is the moment of inertia, and ω is the angular velocity.

2. How does the linear velocity affect the kinetic energy of a rotating and translating bar?

The linear velocity has a direct effect on the kinetic energy of a rotating and translating bar. As the linear velocity increases, the kinetic energy also increases, since it is directly proportional to the square of the velocity in the kinetic energy equation.

3. What role does the moment of inertia play in the kinetic energy of a rotating and translating bar?

The moment of inertia, represented by the symbol I, is a measure of an object's resistance to changes in its rotational motion. It has a direct effect on the kinetic energy of a rotating and translating bar, as it is directly proportional to the square of the angular velocity in the kinetic energy equation.

4. How does the mass of the bar affect its kinetic energy?

The mass of the bar, represented by the symbol m, also has a direct effect on its kinetic energy. As the mass increases, the kinetic energy also increases, since it is directly proportional to the square of the mass in the kinetic energy equation.

5. What happens to the kinetic energy of a rotating and translating bar if it is subjected to external forces?

If a rotating and translating bar is subjected to external forces, such as friction or air resistance, the kinetic energy will decrease. This is because the external forces will do work on the bar, converting some of its kinetic energy into other forms of energy, such as heat or sound.

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