Rotational inertia of a rod that has mass on one end

In summary, a 3 kg mass on the end of a 4 meter metal rod, with a pivot at one end and a mass of 2kg, has a rotational inertia of 10.6. The rotational inertia of the system is the sum of the individual rotational inertias of the rod and the mass. If the mass at the end is assumed to have negligible size, its rotational inertia can be calculated using the equation I=(ML^2)/3.
  • #1
xd14
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Homework Statement


a 3 kg mass is on the end of a metal rod which is pivoted at one end. the mass of the rod is 2kg its length is 4 meters

Homework Equations


I=(ML^2)/3

The Attempt at a Solution


the rotational inertia of the rod itself is 10.6 but i don't know how the 3kg mass at the end would effect things
 
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  • #2
xd14 said:

Homework Statement


a 3 kg mass is on the end of a metal rod which is pivoted at one end. the mass of the rod is 2kg its length is 4 meters

Homework Equations


I=(ML^2)/3

The Attempt at a Solution


the rotational inertia of the rod itself is 10.6 but i don't know how the 3kg mass at the end would effect things
Assuming the mass at the end has negligible size , what is the I of a particle of mass m about a pivot point , and then note the I of the rod-mass system is the sum of the I's of its parts.
 

Related to Rotational inertia of a rod that has mass on one end

1. What is rotational inertia?

Rotational inertia, also known as moment of inertia, is a measure of an object's resistance to change in rotational motion. It depends on the object's mass, distribution of mass, and axis of rotation.

2. How is rotational inertia different from linear inertia?

Rotational inertia is similar to linear inertia in that it describes an object's resistance to change in motion. However, while linear inertia depends on an object's mass and velocity, rotational inertia also takes into account the object's distribution of mass and axis of rotation.

3. How does the position of mass on a rod affect its rotational inertia?

The position of mass on a rod can significantly affect its rotational inertia. The farther away the mass is from the axis of rotation, the higher the rotational inertia will be. This means that a rod with mass concentrated at one end will have a higher rotational inertia than a rod with evenly distributed mass.

4. Does the shape of a rod affect its rotational inertia?

Yes, the shape of a rod can affect its rotational inertia. For example, a thin and long rod will have a lower rotational inertia than a thick and short rod with the same mass. This is because the thin rod has more of its mass concentrated farther away from the axis of rotation, resulting in a higher rotational inertia.

5. How can the rotational inertia of a rod be calculated?

The rotational inertia of a rod can be calculated using the formula I = MR^2, where I is the rotational inertia, M is the mass of the rod, and R is the distance from the axis of rotation to the center of mass. This formula assumes that the mass is evenly distributed along the rod.

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