**Dynamics** is a branch of applied mathematics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to *kinematics*, which studies the motion of objects without reference to its causes. Isaac Newton defined the fundamental physical laws which govern dynamics in physics, especially his second law of motion.

Generally speaking, researchers involved in dynamics study how a physical system might develop or alter over time and study the causes of those changes. In addition, Newton established the fundamental physical laws which govern dynamics in physics. By studying his system of mechanics, dynamics can be understood. In particular, dynamics is mostly related to Newton’s second law of motion. However, all three laws of motion are taken into account because these are interrelated in any given observation or experiment.

Topical Notes, Problems, Presentations, Quiz, Test, Investigations and Videos |

Forces, Types, and representations |

Newton’s First Law |

Newton’s Second Law |

Newton’s Third Law |

The Gravitational Force |

Applications of Newton’s Second Law |

Friction |

Interacting Objects: ropes and pulleys |

Test your Understanding: Chapter 2 MCQ Quiz 1 Here Take Chapter 2 ReQuiz MCQ Quiz 2 Here |

Newton described force as the ability to cause a mass to accelerate. His three laws can be summarized as follows:

**First law**: If there is no net force on an object, then its velocity is constant. The object is either at rest (if its velocity is equal to zero), or it moves with constant speed in a single direction.**Second law**: The rate of change of linear momentum**P**of an object is equal to the net force**F**_{net}, i.e., d**P**/dt =**F**_{net}.**Third law**: When a first body exerts a force**F**_{1}on a second body, the second body simultaneously exerts a force**F**_{2}= −**F**_{1}on the first body. This means that**F**_{1}and**F**_{2}are equal in magnitude and opposite in direction.

Newton’s Laws of Motion are valid only in an inertial frame of reference.