1. Do Now:

2. Forces
Essential Question: What is a force and do we need them for Newton’s first Law?

3. Objectives
Students will conceptually learn about forces, Gravity and Inertia.

4. What is a force? Definition: A push or pull applied to an object.
Net Force: When two or more forces act on an object at the same time.

5. Types of forces
Friction: the force that is created whenever two surfaces move or try to move across each other.
Friction is caused by microscopic bumps on surfaces called microwelds.
(ex: Static, sliding, rolling, fluid)
Air Resistance: is the frictional force air exerts against a moving object.
As an object moves, air resistance slows it down.

6. Balanced VS Unbalanced Forces
Unbalanced forces: Can cause an object to start moving, stop moving, and change direction.
Balanced Force: Equal forces acting on one object in opposite directions. Balancing forces acting on an object DO Not change objects' motion.

7. What is Gravity?
Definition: any two masses that exert an attractive force on each other.
Gravity depends on mass and distance between objects.
Weight: Gravitational force exerted on an object; measured in units called Newton’s.

8. What is Thrust?
Definition: is the force that propels a flying machine in the direction of motion.
Engines produce thrust

9. How to draw a freebody diagram?
1. list all the forces acting on the object.
2. Draw an arrow of the direction that the forces is acting in.

10. Example #1

11. Example #2

12. Newton’s First Law
Definition: An object in motion stays in motion or an object at rest stays at rest until an unbalanced net force acts on it.