This document discusses forces and friction. It defines friction as the force that slows down moving objects and is caused by two surfaces rubbing together. It explains that there is more friction between rough surfaces than smooth surfaces, making it harder to push or pull objects over rough surfaces. It also discusses how applying different amounts of force can change an object's motion by starting, stopping, speeding up, slowing down, or changing its direction of movement. The document aims to teach students about how surfaces can affect the forces on objects and how forces and their directions can change an object's motion.

1. 1

2. Ch.11, Lesson 2
Forces and Change
What slows things down?
 Is a force that slows down
moving things.
 It happens when 2 things rub
together.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
2
Friction

3. Ch.11, Lesson 2
Forces and Change
 There is more friction between
rough surfaces than between
smooth ones.
 It is harder to push or pull
something over a rough surface
than over a smooth one.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
3

4. Ch.11, Lesson 2
Forces and Change
 When you skate, your wheels
move along a surface.
 To stop, you drag a rubber
stopper on the ground.
 You will slow down until you
stop.
 Because dragging causes
friction.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
4

5. Ch.11, Lesson 2
Forces and Change
What happens when you
change a force?
• When a force changes, the way
a thing moves changes, too.
• A little force can make a golf
ball move slowly.
• More force can make the golf
ball move faster and farther.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
5

6. Ch.11, Lesson 2
Forces and Change
 It takes more force to move
heavy things than it does to
move light things.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
6

7. Ch.11, Lesson 2
Forces and Change
How can force change motion?
When something moves, it is in
motion.
A force can change the motion of
things, it can make:
 object start moving.
 Moving object speeds up.
 Moving object slows down
 Moving object changes direction.
 Moving object stops moving
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
7

8. Ch.11, Lesson 2
Forces and Change
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
8

9. Ch.11, Lesson 2
Forces and Change
 When you play table tennis, you
use a paddle to hit the ball
across the net.
 Each hit is a push.
 The push changes the direction
of the ball.
 The ball moves back and forth.
Vocabulary:
Friction
Objectives:
I will be able to know:
1-how surface can
change the force on
an object.
2-define and
understand friction
3-understand how a
force and direction of
force can change.
9