AIM: What is friction? Describe different types of Friction. Define the parts of a spring scale.

AIM: What is friction?

Describe different types of Friction.

Define the parts of a spring scale.

Spring scale, pointer, spring, hook, friction, sliding friction, air resistance, rolling friction

AIM: What is friction?

What is the basic unit of measure of length in the metric system for length?

Meter

What is the basic unit of measure for mass in the metric system?

Gram

What is the basic unit of measure for volume?Liter

What is the basis unit of measure for force?

the NEWTON … N

On earth it take a force of approximately 10 N to lift a 1 Kg object

What is Friction?

Definition: Friction is the force which opposes the motion of an object.

EVERYBODY: Push your notebook across the table.

Why does it stop?

Three types of Friction:

1. Sliding Friction,

2. Rolling Friction,

3. Air Resistance

DEMONSTRATE: Sliding Friction

Push a chair across a room.

Does it stop?

Why: Sliding Friction

DEMONSTRATE: Rolling Friction

Slide a rolling chair across the room.

Does is stop?

Eventually

But does it move farther with the wheels then without?

Absolutely

DEMONSTRATE: Air Resistance

•Drop a flat piece of paper•Drop a crushed piece of paper•Can YOU explain why the flat piece took longer to reach to ground.

Is friction bad?

•Without friction, it’d be like walking on ice•Imagine peddling your bicycle on ice.

•Or wearing smooth soled shoes while playing basketball?

What is “that hand” holding?

… a spring scale

Parts of Spring Scale

Hook

Pointer

Spring

Is this a spring scale?

YES. Most scales are spring scales!

DON’T confuse a scale with a triple beam

balance. They are two different

things.

** Activity:

Using a Spring Scale.

1.Mass a book and several other small objects.2.What is the weight of the book?3.What are you measuring when you when you weigh an object? (gravity)

How much force (measured in N’s) does it take to lift a 1 Kg object?

10 Newtons

REVIEW VOCABULARY – AND THE AIM – AND THE OBJECTIVES

Define the parts of a spring scale.

Hook, pointer, spring

Describe three different types of friction: Sliding, rolling, air resistance

Class Activity:

W/S Concepts 2-3, 2-5

Homework:

INTERNET QUESTIONS

FINISH W/S