# Special theory of relativity

Calculator name | Summary |

Special relativity (Lorentz contraction) | Calculates the length contraction of a body moving with some relative velocity with respect to the observer. |

Special relativity (time dilation) | Calculates the time dilation of a body moving for some time with some relative velocity with respect to the observer. |

Special relativity (composition of velocities) | Calculates the composition of two velocities. |

Special relativity (mass-energy) | Calculates the mass-energy of a body moving with some relative velocity with respect to the observer. |