GEN PHYS 1 | Dynamics

Dynamics

study of the cause of motion

Force

• push and pull on an object

• interaction between two objects or between an object and its environment

Contact Forces

physical contact between two objects

Non-contact Forces

forces that act through empty space

Normal Force (N or F_N)

• force exerted on an object by any surface with which it is in contact

• perpendicular to surface

Friction (f)

• a force exerted on object that acts parallel to surface but opposite to the direction of the force

Tension Force (T)

• pulling force by string or cord that suspends an object in the air

Weight (W) Formula

Let

• m = mass

• g = force of gravity

W=mg

First Law of Motion

A body at rest remains at rest or if in motion, remains in motion with a constant velocity, unless acted on by an external force.

Inertia

A property depending on mass. As the mass increases, the inertia also increases.

Second Law of Motion

The acceleration of an object is in the same direction as the force exerted on the object. This force is equal to the product of the mass of the object and its acceleration.

F=ma

Third Law of Motion

If object A exerts force on object B, then object B exerts a force on object A that is equal in magnitude but opposite in direction.

Free Body Diagram

• systematic representation of all forces on an object

• denoted by arrows and symbols

• size indicates magnitude

• direction of arrows indicates direction of magnitude