1. Forces and the Laws of Motion
Newton’s First Law

2. Inertia
1630 – Galileo – an objects tries to maintain its state of motion
Expanded on by Sir Isaac Newton in 1687 as his First Law of Motion
An object at rest remains at rest, and an object in motion continues in motion with constant velocity (constant speed in a straight line) unless the object experiences a net external force

3. Inertia Inertia – tendency of an object not to accelerate
First Law of Motion is also known as the Law of Inertia
When the net external force on an object is zero, its acceleration (or change in its velocity) is zero

4. Inertia
Net external force – the total force resulting from a combination of external forces on an object; sometimes called the resultant force
Calculated like vectors
Break forces down into x and y components
Add x and y component forces
Use Pythagorean theorem and inverse tangent to find resultant force and angle
Acceleration is determined by net external force

5. Inertia

6. Inertia

7. Inertia Mass can be considered a measurement of inertia
Large masses must overcome more inertia than small masses to change velocity

8. Equilibrium
Equilibrium – the state in which there is no change in a body’s motion
Exists when net external force equals zero