# Should I consider Linear Kinetic Energy in this Equation

• Vichakron
In summary, the conversation discusses the calculation of torque from deriving kinetic energy for a system with a rotating object causing linear motion. The main question is whether linear kinetic energy should be considered, and different equations are proposed to calculate torque for a rolling disc. It is also mentioned that the total energy of the system must be taken into account, including potential, kinetic, and rotational energy.
Vichakron
Sorry If the thread name confuse you.
I want to know if I want to find the Torque from deriving Kinetic Energy and the system has Object the Rotate and the rotating cause linear motion(v).
Let's say it a Rolling Disc on the non-slope plane which has angular velocity ω and that ω cause it to move forward at velocity v.

Should I consider Linear Kinetic Energy? which I think will result,
τ=d(½Mv2+½Iω2)/dθ
τ=(I+Mr2
or shouldn't I?
τ=Iα.

Sorry if my question wasn't clear or my English was confusing.

Welcome to PF.
A rolling disc has potential, kinetic and rotational energy. You must account for the total.
For a disc it is the centre of rotation that is important. The moment of inertia is a function of mass and section.
You must add the angular KE about the centre to the linear KE of the centre.
Where the height of the centre changes you must also include PE.

Vichakron
Baluncore said:
Welcome to PF.
A rolling disc has potential, kinetic and rotational energy. You must account for the total.
For a disc it is the centre of rotation that is important. The moment of inertia is a function of mass and section.
You must add the angular KE about the centre to the linear KE of the centre.
Where the height of the centre changes you must also include PE.

Thank you so much for the answer.

## What is linear kinetic energy?

Linear kinetic energy is the energy an object possesses due to its motion in a straight line.

## How is linear kinetic energy calculated?

Linear kinetic energy is calculated using the equation KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity.

## When should I consider linear kinetic energy in an equation?

You should consider linear kinetic energy in an equation when the object in question is moving in a straight line and its motion is a significant factor in the problem at hand.

## Are there any limitations to using linear kinetic energy in equations?

Yes, linear kinetic energy is only applicable to objects moving in a straight line and does not take into account factors such as rotation or potential energy.

## What are some real-world applications of linear kinetic energy?

Linear kinetic energy is important in various fields such as engineering, physics, and sports. It is used in designing structures, calculating the force of impact in collisions, and determining the speed of projectiles, among others.

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