1. ACTIVITY #46: NEWTON’S LAWS OF MOTION

2. Newton’s 1st Law of Motion

3. Newton’s First Law of Motion
An object at rest remains at rest, and an object in motion remains in motion, until an unbalanced force acts on it.

4. In Other Words
If an object is at rest or in motion at a constant speed and in a straight line, the forces acting on it are balanced.

5. What is the motion in this picture
What is the motion in this picture? What is the unbalanced force in this picture? What happened to the skater in this picture?

6. Gravity
Table
Both of these forces are acting on the
papers and are balanced.

7. Force of wind
These forces are
balanced so the
boat moves at a
constant speed in
a straight line.
20 mph
Air/Water Resistance

8. Inertia The tendency of an object to remain at rest or in motion.
The greater the mass of an object, the greater the force needed to cause a change in its motion. (Its inertia is greater)

9. Which object has more inertia?
30 mph
30 mph

10. Which object has more inertia?
                                      
Both at rest

11. Inertia in Real Life
When you are riding in a car you are moving in the same direction and at the same speed as the car. If the car suddenly stops (hits another car or a wall) you will continue to move in the same direction and at the same speed until an unbalanced force (the windshield) acts upon you.

12. Inertia

13. How does a seat belt protect people from this effect?
Inertia in Real Life
How does a seat belt protect people from this effect?

14. Inertia in Real Life Continued
If you are riding in a car that is traveling in a straight line and then makes a sharp left, what happens to you? Why?
                                      

15. Inertia in Real Life Continued
What happens to you when the car you are riding in accelerates hard? Why?

16. Some More Examples from Real Life
A soccer ball is sitting at rest. It takes an unbalanced force of a kick to change its motion.
Two teams are playing tug of war. They are both exerting equal force on the rope in opposite directions. This balanced force results in no change of motion.