Kinetic Energy Concerns Movement of Matter
by Ron Kurtus
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 = mv2/2
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
- v2 is the velocity squared or 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.
KErot = Iω2/2
where
- KErot is the rotational kinetic energy, measured in joules (J)
- I is the moment of inertia in kg-m2
- 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
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Kinetic Energy Concerns Movement of Matter