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Demonstration: Egg Drop!What is the initial motion of the egg?

The egg is at rest.

What causes the egg to change motion?

The force of gravity causes the egg to fall into the cup.

How does this model the law of inertia?

When the tube and pie tin are removed, the egg stays at rest for a split second before

gravity acts on it.

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Demonstration: Egg Drop!Which objects are put into motion in this

demo?The pie tin, paper towel tube, and egg.

All these objects have inertia. Which of these objects are easier to move? What makes these objects easier to move?

What gives an object more inertia?The more mass an object has, the more inertia it has, and the more force it will

take to change its state of motion

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What is Mass?Amount of matter in an object (how much “stuff” is in an object)

Mass is the measure of the inertia of an object

SI Units: kilograms (kg)The more mass an object has, the more

inertia it has, and the more force it takes to change its state of motion

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QUICK NOTE: In order to get something to move,

the force applied must be big enough to overcome the inertia

Ex. If you push a desk with a small force it will not move because the force is not big enough to overcome the inertia of the desk (a desk at rest wants to remain at rest)

William “the Refrigerator” Perry vs. a little person

Who has more mass? Who has more inertia? Why?

William Perry

William Perry because mass is a measure of inertia

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What is Volume?The amount of 3-dimensional space an object takes up

SI unit: liters (L)

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Mass is NOT Volume

Which of the following objects has more mass? More volume?

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What is Weight?The force of gravity on an objectSI units: Newtons (N)Weight depends on an object’s location!!

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Mass is NOT Weight

Is mass the same on Earth and the moon? Is weight the same on the Earth and the moon? What would the units be in this cartoon?

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What’s the relationship between mass and weight?

Mass and weight are proportional to each other in a given place

weight=(mass x acceleration)On Earth: weight=mass x 9.8m/s2

Many people approximate so weight=mass x 10

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Stop and Jot

Your car gets towed and crushed. What happens to…

Mass:

Inertia:

Volume:

Weight:

Stays the same

Stays the same

Stays the same

Decreases

10 Minute Practice1. If the mass of an object is doubled, what will happen

to its inertia?2. Sally goes on a diet, what happens to her inertia?

Why?3. Put the following examples in order from greatest

inertia to smallest inertia. 55-kg model 80-kg track and field athlete 12-kg dog 150-kg man who eats his feelings

4. Calculate the weight (in N) of a 2000 kg elephant5. Calculate the weight (in N) of a 2.5 kg melon6. An apple weighs about 1N on earth. What is its mass

(in kg)?7. Wrap up question: Explain how weight and mass are

different. What is the relationship between the two? 12