1. Chapter 11 Section 3
Motion and Forces

2. Answer these questions– Use your own paper.
Green Lantern hits his archenemy Sinestro, causing him to fly backwards from 40 km/h to 90 km/h in 2 seconds. Find acceleration. (**Remember to check your units**)
How long will it take a cyclist with an acceleration of m/s2 to bring a bicycle with an initial forward velocity of 13.5m/s to a complete stop?

3. Important Vocabulary
Force
Friction
Static Friction
Kinetic Friction

4. Reading guide notes – 11.3
If you attach a spring scale to something very heavy, such as an 18- wheeler truck, and pull very hard on the spring scale, chances are that the truck will _______. It will remain at _______ The spring scale would show that you really are exerting a force, but your force is not producing any motion. __________ that if an object is at rest, there are no forces acting on the object, but this is not necessarily true. You could exert a HUGE force on the truck by pulling on the spring scale, but the truck probably will not move because: ________________________________________________________________ ______________________________________________________

5. What is a Force?

6. Forces vary in strength and can act through contact or at a distance.
11.3 RG
A force is defined as any action that can change the state of motion of an object. A force has both magnitude and direction.

7. What do scientists identify as the fundamental forces of nature
What do scientists identify as the fundamental forces of nature? Four Fundamental Forces in Nature
READING GUIDE NOTES 11.3
Force of Gravity – we will discuss gravity in the next Chapter
Electromagnetic Force
Strong Nuclear Force
Weak Nuclear Force

8. Two of these, the s ______and w______________ act only over very short distances, so you do not experience them in e_____________
The s______________ holds protons and neutrons together in the n______of a______.
It is the s___________of all the forces.
The g______________ and e___________ forces act over longer distances. The e_______________force is about 1/100 as strong as the strong nuclear force. The g________________force is even weaker than that.

9. Two of these, the strong nuclear force and weak nuclear force, act only over very short distances, so you do not experience them in everyday life.
The strong nuclear force holds protons and neutrons together in the nuclei of atoms. It is the strongest of all the forces. The gravitational and electromagnetic forces act over longer distances. The electromagnetic force is about 1/100 as strong as the strong nuclear force. The gravitational force is even weaker than that.

11. The forces we are most familiar with, like pushing and pulling, are examples of c________forces. They involve touching things in order to exert a force on them.
Field forces, such as the attraction of g________ or the repulsion between two n_____________ do not require that objects t_______ each other.
Both contact and field forces can c_____________or to _______________

12. The forces we are most familiar with, like pushing and pulling, are examples of contact forces. They involve touching things in order to exert a force on them.
Field forces, such as the attraction of gravity or the repulsion between two north poles of a magnet, do not require that objects touch each other.
Both contact and field forces can cause an object to move or to stop moving .

13. What happens when there is a net force acting on an object?

14. When two forces acting on the same object are unequal, the forces are u .
The combination of all forces acting on an object is called the n on that object. This combination of forces is what determines whether the object will c_____________________________
(A change in the speed or direction of an object is called a )

15. When two forces acting on the same object are unequal, the forces are unbalanced.
The combination of all forces acting on an object is called the net force on that object. This combination of forces is what determines whether the object will change its motion. (A change in the speed or direction of an object is called acceleration.)

16. If there is a net force acting on an object, the object __________________________.
If the net force is zero, the object will ________________
Forces are said to be _________if they produce a net force of zero.
Balanced forces do not cause an object at rest to ___________
and balanced forces do not ________________________________a moving object.

17. If there is a net force acting on an object, the object accelerates in the direction of the net force. If the net force is zero, the object will not accelerate.
Forces are said to be balanced if they produce a net force of zero. Balanced forces do not cause an object at rest to start moving, and balanced forces do not cause a change in the motion of a moving object.

18. When two or more forces are acting on the same object in the SAME direction, you ADD the forces.
When two or more forces are acting on the same object in OPPOSITE directions, you subtract the forces.

19. If a person pulls on a cart to the right with a force of 10N and
another person pulls to the left with a force of 3N, what is the net force?
Is it balanced or unbalanced?
3 N N
net force = _____ ____________________________
Which direction would the cart move? _____________

20. net force = _____ ______________________________
If a person pulls on a cart to the right with a force of 5N
and another person pulls to the left with a force of 15N,
what is the net force? Draw direction arrows. Is it balanced or unbalanced?
Draw direction arrows!
15 N N
net force = _____ ______________________________
How could the two people make their forces balanced? _____________________________________________

21. Picture with Caption Layout
If forces act on an object in different directions that are not opposite to each other, like this, the directions are combined into a single force and the acceleration of the object will be in a direction of that combination of the other forces.
Draw an arrow to indicate which way you think the box
will accelerate.
50 N
What happens when there is a net force acting on an object?
80 N

22. Picture with Caption Layout
14. If forces act on an object in different directions that are not opposite to each other, like this, the directions are combined into a single force and the acceleration of the object will be in a direction of that combination of the other forces.
50 N
What happens when there is a net force acting on an object?
80 N
15. Draw an arrow to indicate which way you think the box
will accelerate.

23. What would the world be like without friction?

25. State the 2 major types of frictions and their definition
State the 2 major types of frictions and their definition Static friction vs Kinetic Friction

26. Why is friction necessary. How can helpful friction be increased
Why is friction necessary? How can helpful friction be increased? How can unwanted friction be lowered?

27. Picture with Caption Layout
QUICK REVIEW:
Write and answer on your paper.
What force always opposes motion?
List 2 types of kinetic friction. Which one is less?
Picture with Caption Layout

28. Assignments for Chapter 11
(HS)
(MS)
Textbook pg. 388 Graphing Motion
Textbook pg 390, #1-17
Textbook pg 392, #1-11
Textbook pg