# Newton's First Law of Motion

• An object at rest will remain at rest, and an object in motion will remain in motion, at constant velocity and in a straight line, un line acted upon by a net force

• An object will continue in its current state of motion unless an unbalanced force acts upon it

• An object at rest will remain at rest unless an unbalanced force acts upon them

• Also known as the law of inertia

# Force

• A force is a push or pull on an object

• Unites of force are newtons (N)

• Contact Force Field Force
Tension
Applied Force
Friction
Gravity
Electrical Force
Magnetic Force

# Net Force

• A net force is the vector sum of all the forces acting on an object

• If all forces are balanced, there is no net force. This situation is known as translational equilibrium

• An unbalanced force is a net force

# Equilibrium

• Static Equilibrium

• Net force on an object is 0

• Net torque on an object is 0

• Object is at rest

• Mechanical Equilibrium

• Net force on an object is 0

• Net torque on an object is 0

• Translational Equilibrium

• Net force on an object is 0

# Inertia

• Inertia is the tendency of an object to resist a change in velocity

• Mass actually has two aspects

• Inertial mass is how hard it is to change an object's velocity

• Gravitational mass is how strongly a gravitational field affects a mass

• For the purposes of basic introductory physics, mass and inertia are synonymous

# Free Body Diagrams

• Tools used to analyze physical situations

• Show all the force acting on a single object

• Object itself drawn as a dot or rectangle 