First Definition for Kinetic Energy

When something is in motion it is said to have kinetic energy.

Formula for Kinetic Energy

For an object that is moving the kinetic energy equals one half times the mass of the object times the square of the speed of the object. In symbols:

E_{K} = (1/2)mv^{2}

Example Calculation for Kinetic Energy

How much kinetic energy does an object have if its mass is 5.0 kg and it is moving at a speed of 4.0 m/s?

E_{K}= (1/2)mv^{2} |
Formula for kinetic energy. |

E_{K}= (1/2)(5.0 kg)(4.0 m/s)^{2} |
Plug in values for mass, 5.0 kg, and speed, 4.0 m/s. |

E_{K}= 40 J |
Kinetic Energy equals 40 J. |

Here are some problems to try using the above equation: