1. Motion & Forces
Chapter 2.3

2. Forces
Push or pull
Anything that can change the motion (speed) of an object

3. Balanced Forces Forces that do not change the speed of an object
Two forces that oppose each other (opposite directions) and are the same magnitude (equal in size) cancel each other out
Net force (combined forces) = 0 N

4. Unbalanced forces
When two forces act on an object but are not equal in magnitude (size) and/or not in opposite directions
Always results in a change in speed of an object

5. Calculating Net Forces
Practice Question 1: Calculate the net force for the object shown:

6. Calculating Net Forces
Practice Question 2: Calculate the net force for the object shown:

7. Calculating Net Forces
Practice Question 3: Calculate the net force for the object shown:

8. Inertia The tendency of an object to resist a change in its motion
NEWTON’S FIRST LAW OF MOTION
An object at rest stays at rest or an object in motion stays in motion unless a force acts upon it
The speed of an object will not change unless a new force acts on the object

9. Practical Question:
Using Newton’s First Law of Motion, explain why we need to wear seat belts?