1. Force and Newton’s First Law 2.1 pp. 28-31 Mr. Richter

2. Agenda  Warm-Up  Review HW  Notes  Review definition of Force  Newton’s First Law  Inertia  Acceleration and F = ma practice

3. Objectives: We Will Be Able To…  Recognize that force is needed to change an object’s motion.  Explain Newton’s First Law (N1L)  Describe how inertia and mass are related.

4. Warm-Up:  A boy pulls a 10-kg box to the right with a force of 200 N, while his little brother pulls against him with a force of 50 N. 1.What is the net force acting on the box? 2.What is the acceleration of the box? (This is the type of problem you can expect to see on Monday’s quiz)

5. Newton’s First Law Force, Mass, and Inertia

6. What is Force?  A push or a pull.  A force is required to change an object’s motion.  There can be no change in motion without the presence of a force.

7. Newton’s First Law (N1L)  An object at rest will stay at rest and an object in motion will continue in motion with the same speed and direction UNLESS acted on by a force.  Objects want to keep doing what they’re doing. It takes a force to change them.  N1L is sometimes called “The Law of Inertia”

8. Inertia  Some objects resist changes in motion better than others.  Inertia is a measure of the ability of an object to resist changes in motion.  A bowling ball and a golf ball roll at the same speed. Which is easier to stop?

9. Inertia  The more mass an object has, the more inertia it has. Mass and inertia are very closely related.  The more inertia an object has, the more force is required to change its motion.

10. Wrap-Up: Did we meet our objectives?  Recognize that force is needed to change an object’s motion.  Explain Newton’s First Law (N1L)  Describe how inertia and mass are related.

11. Homework  Finish Study Guide for tomorrow.  Reminders:  No-stakes math test tomorrow  Quiz Monday: Force 2.1 and 2.2