# Dynamics

Dynamics is the part of physics that describes the time evolution of a physical system in relation to the causes of changes in physical and/or movement state.

Dynamics’ aim is to describe factors that may cause alterations of a physical system, quantify them and raise equations of motion or evolution equations for that operating system.

Dynamic Laws: They were formulated by Isaac Newton and thanks to them we can predict the movement of a body if we know its current status and the forces which are acting on it.

• Inertia Law: “If the result of the forces which are acting on a body is zero or does not exist any external force, it is that if the body is at rest, it is going to continue to do so and if he moved with rectilinear uniform movement, it will continue to move with that same movement.”
• Fundamental Dynamics Law: “If on a body is acting a resultant force, it acquires a acceleration that is directly proportional to the force applied, being the body mass the proportionality constant. This acceleration has the same direction as the resultant force Bioprofe |Dynamics theory| 01

• Action and reaction principle: “If a body exerts a force on another body, this one at the same time, turn exerts a force on the first one with the same magnitude and direction, but opposite.” Bioprofe |Dynamics theory| 02

The negative sign means the opposite direction. The forces do not be cancelled because they act on different bodies.

Hooke’s law: A body is elastic when it regains its shape after stopping the forces that had deformed it. In the case of a spring, the deformation (elongation) is directly proportional to the applied force.
The elastic bodies have elasticity limits within which Hooke’s law is fulfilled, if these limits are exceeded, the body does not obey this law and its deformation can be permanent.
The dynamometer is based on this law.

FORMULA SUMMARY:

Fundamental equation of the Dynamics Bioprofe |Dynamics theory| 03

Centripetal and centrifugal forces Bioprofe |Dynamics theory| 04

Tensions

Object that rises Bioprofe |Dynamics theory| 05

Object that goes down Bioprofe |Dynamics theory| 06

Atwood machine Bioprofe |Dynamics theory| 07

Friction (µ = coefficient of friction ; N = Normal Force) Bioprofe |Dynamics theory| 08

Friction on a horizontal plane Bioprofe |Dynamics theory| 09

Friction on an inclined plane Bioprofe |Dynamics theory| 10

Radius of curvature with cant and friction Bioprofe |Dynamics theory| 11

Mechanical impulse Bioprofe |Dynamics theory|12

Linear momentum or Quantity of movement Bioprofe |Dynamics theory|13

Theorem of the mechanical impulse Bioprofe |Dynamics theory|14

Angular or kinetic momentum Bioprofe |Dynamics theory|15

Theorem of the angular momentum Bioprofe |Dynamics theory|16

Hooke’s Law Bioprofe |Dynamics theory|17