1. Newton’s First Law of Motion - Inertia
Unit 3
Newton’s First Law of Motion - Inertia

2. Section 3-1 Evolution of Motion
Aristotle: BC
Natural Motion
Objects have natural resting places
Heavy Stuff Falling, Light stuff Rising, Circular Motion
Violent Motion
Forced Motion from pushing or pulling
A force is needed to make an object move from its natural rest.

3. Section 3-1 Evolution of Motion
Evolution of Forced Motion
Copernicus
Described Earth’s Motion
Earth is Moving
Only way to Explain the Motion of Planets
Contradicts Aristotle’s Natural Rest

4. Section 3-1 Evolution of Motion
Evolution of Forced Motion
Galileo
Forces aren’t needed to keep things moving
Friction makes things slow down
Gravity changes the speed of objects

5. Section 3-1 Evolution of Motion
Galileo answer How things moved, not why!

6. Section 3-1 Evolution of Motion
Galileo answer How things moved, not why!

7. Section 3-1 Evolution of Motion
Inertia: A characteristic of an object that resists any change in motion.
Complete the venn diagram comparing and contrasting Aristotle and Galileo’s ideas on motion. [#2 on Checklist]

8. Section 3-1 Evolution of Motion
Evolution of Forced Motion
Isaac Newton
Published a paper that defined the Laws of Motion
First Law - Inertia
Second Law – Acceleration
Third Law – Action & Reactions

9. Section 3-1 Evolution of Motion
Time Line
400 BC
300
200
100
100 AD
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
Aristotle
Copernicus
Galileo
Newton
Present Day

10. Section 3-1 Evolution of Motion
Concept Questions to Answer in Small Groups
A ball is rolled across a counter top and rolls slowly to a stop.
How would Aristotle interpret this behavior?
How should you interpret this behavior?

11. Section 3-1 Quiz Quiz will be on : _____________________
Topics you need to Study:
History of Motion – Which Scientist were responsible for Specific Ideas
Vocab – Inertia, Force & Friction

12. Section 3-2 Newton’s 1st Law
Broken Brick - Demonstration & Notes
Sketch
Description of Observation
Initial Explanation of Observation
Final Explanation of Observation

13. Section 3-2 Newton’s 1st Law
Newton’s 1st Law: Every object continues in a state of rest, or of motion in a straight line at constant speed, unless it is compelled to change that state by forces exerted upon it.
WHAT DOES THIS MEAN!!!!!

14. Section 3-2 Newton’s 1st Law

15. Section 3-2 Newton’s 1st Law
Concept Questions to Answer in Small Groups

16. Section 3-2 Newton’s 1st Law
Concept Questions to Answer in Small Groups

17. Section 3-2 Newton’s 1st Law
Inertia Review – Objects don’t like to change their motion. Their “Laziness”
Which of the following objects would be the hardest to kick?
A. An Empty Can
b. A can filled with water
C. A can filled with Lead

18. Section 3-2 Newton’s 1st Law
The amount of inertia in an object depends on its mass.

19. Section 3-2 Newton’s 1st Law
Can you use Newton’s 1st law of motion to explain what has happened in the pictures below.

20. Section 3-2 Newton’s 1st Law
Misconception ALERT!!
Don’t confuse size (volume) with mass.

21. Section 3-2 Newton’s 1st Law
Comparing Mass and Weight
Mass
Weight
The amount of Matter in an object.
The force of gravity on an object (how hard the object is pulled down)
S.I. Unit = Kilograms
S.I. Unit = Newtons
Measured with Balance
Measured with Spring Scale
Same on any planet or in deep space.
Changes based on the planets gravity and is Zero in deep space.
A Calculated Value: W = m · g

22. Section 3-2 Newton’s 1st Law
Concept Questions to Answer in Small Groups
Compare a 2-kg iron block to a1-kg iron block.
Does it have twice the mass?
Does it have twice the inertia?
Does it have twice the volume?
Does it have twice the weight on Earth?

23. Section 3-2 Newton’s 1st Law
Concept Questions to Answer in Small Groups
Compare a 2-kg bunch of Bananas to a 1 kg loaf of bread.
Does it have twice the mass?
Does it have twice the inertia?
Does it have twice the volume?
Does it have twice the weight on Earth?

24. Section 3-2 Newton’s 1st Law
Read Text book Page 55
Summarize the important information in your notebook. Try and Guess the Notes.

25. Section 3-2 Newton’s 1st Law
Inertial Reference Frame Video

26. Section 3-2 Newton’s 1st Law
Concept-Development Practice Page 4-1
[#6 on Checklist]
Complete the Front and Back

27. Section 3-2 Quiz Quiz will be on : _____________________
Topics you need to Study:
Newton’s 1st Law of Motion
Mass vs. volume vs. Weight

28. Book Assignment
Pages 56 & 57
6 – 14, 21 – 25, and 26 – 30.

29. Section 3-3 Net Force
Forces are Vectors

30. Section 3-3 Net Force
Some Common Forces we will measure and investigate in Class.
Applied Forces Weight Normal Force

31. Section 3-3 Net Force
More than one force can act on an object at a time.
Net Force: The combination of all the forces acting on an object.

32. Section 3-3 Net Force
Equilibrium is when the net force on an object equals zero.

33. Section 3-3 Net Force Equilibrium = static Motion = Balanced Forces
Misconception Alert!!!
Can an object be moving and still have a net force of zero?
If an object is in equilibrium, does it mean that no forces are acting on it?
Can an object be in equilibrium and have a non-zero net force?

34. Section 3-3 Net Force Understanding Equilibrium
If the net force is zero, how much does each string need to pull up on the block?

35. Section 3-3 Net Force Understanding Equilibrium
What happens if the strings aren’t vertical?

36. Section 3-3 Net Force Concept Questions to Answer in Small Groups
Explain why a rope could be used to safely hang a tire swing, but might break if used as a clothes line and you hang on it?

37. Section 3-3 Net Force Concept-Development Practice Page 4-2
[#9 on Checklist]
Complete the Front and Back

38. Section 3-3 Net Force Calculating Net Force
Net force is a result of all the forces acting on an object.
Calculate Net Force like any other resultant vector.

39. Section 3-3 Net Force
Determine the Net force on the mass for each scenario.

40. Section 3-3 Net Force
Find the net force on the box.
4 N
2 N
5 N

41. Section 3-3 Net Force Concept-Development Practice Page 4-2
[#10 on Checklist]
Complete the Front and Back

42. Section 3-3 Quiz Quiz will be on : _____________________
Topics you need to Study:
Motion of Objects when in equillibrium
Calculating Net Force

43. Unit 3 Quick VideoReview
Flipping Physics - Introduction to Newton’s First Law of Motion