# Kinetic Energy Concerns Movement of Matter

by Ron Kurtus (revised 9 October 2014)

A moving object is said to have **kinetic energy** that can be transferred to another object. The motion can be translational (in a straight or curved line), according to the equation **KE = ½ mv²**. This equation is valid provided that the speed of the object does not approach the speed of light.

Kinetic energy can also be rotational about an axis or as a vibration.

Motion and kinetic energy can be a direct result of a force can be applied to a object. Also, releasing potential energy can create kinetic energy, such as with springs and chemical reactions. Most forms of energy where material is moving are kinetic energy.

Questions you may have include:

- What does the equation
**KE = ½ mv²**mean? - How can a force create kinetic energy?
- What are other forms of energy?

This lesson will answer those questions. Useful tool: Units Conversion

## Translational kinetic energy

Most of the kinetic energy you see is translational—meaning that the object moves in a straight or curved line. The equation for translational kinetic energy is:

KE = mv^{2}/2

where

**KE**is the kinetic energy, usually measured in joules**m**is the mass of the object, usually measured in kilograms**v**is its speed or velocity of the object, measured in meters per second**v**is the velocity squared or^{2}**v**times**v**

### Can transfer energy

When a moving object collides with another object, some of its **KE** can be transferred according to the *Law of Conservation of Energy* and *Law of Conservation of Momentum*.

### Scale a KE

Kinetic energy covers a wide range of scales. A moving subatomic particle has **KE**, according to its mass and velocity. Likewise, a moving truck has its own **KE**.

## Rotational kinetic energy

An object or particle that is rotating has kinetic energy that can be transferred to another object.

KE_{rot}= Iω^{2}/2

where

**KE**is the rotational kinetic energy, measured in joules (J)_{rot}**I**is the moment of inertia in kg-m^{2}**ω**is the angular velocity in radians per second (rad/s)

The moment of inertia of an object depends on the distribution of its mass. Thus, there is no simple calculation of **I**.

### Can transfer energy

When a spinning object comes in contact with another object, some of its **KE** can be transferred by friction or other resistive force.

### Scale a KE

On the macro scale, an object that comes into contact with a spinning wheel can be projected forward.

On the micro scale, a rotating molecule can affect others through electromagnetic forces.

## Vibrational kinetic energy

An object that is vibrating or oscillating has kinetic energy that can be transferred to another object.

## Summary

Kinetic energy is the energy of a moving object according to the equation **KE = ½ mv²**. Motion and kinetic energy can be a direct result of a force can be applied to a object. Releasing potential energy can create kinetic energy, such as with springs and chemical reactions. Heat, electrical energy and light are forms of kinetic energy.

Move with kinetic energy

## Resources and references

### Websites

### Books

**Top-rated books on Energy Physics**

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## Kinetic Energy Concerns Movement of Matter