MASS, WEIGHT, AND GRAVITY

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WHAT IS MASS?

Mass is a measurement of

the amount of matter in an

object

WHAT IS MATTER?

Matter is what makes up every object

in our universe.

Atoms are the smallest whole units of

matter

All objects in the universe consist of

atoms

SO,WHAT IS MASS AGAIN?

Since mass is a measurement of the

amount of matter in an object, then:

AN OBJECT’S MASS DEPENDS ON TWO

THINGS:

1. The number of atoms that the object

contains/consists of

2. How massive (heavy, large) the atoms

in the object are.

WHICH

HAS A

HIGHER

MASS-

VINCE

WILFORK

OR TOM

BRADY?

WHY?

Vince Wilfork has more mass.

He and Tom are made of the same kinds of atoms, but…

Vince is clearly larger than Tom, so…

Vince is made of more atoms than Tom, so he has more mass.

WHICH HAS A HIGHER MASS-

A BLOCK OF WOOD OR A BLOCK

OF METAL?

WHY?

The block of metal has more mass.

Each is about the same size, but…

The metal block is made of heavier atoms, so…

Since its atoms are more massive, the block of metal has more mass.

WHICH HAS A HIGHER MASS-

THE BOWLING BALL OR

THE SOCCER BALL?

WHY?

The bowling ball has more mass.

Each is about the same size, but…

The bowling ball is solid, so…

it is made of more atoms than the “hollow”soccer ball, so it has more mass.

MASS IS MEASURED BY A TRIPLE BEAM BALANCE

ZEROING:

TO MOVE POINTER UP ABOVE THE

ZERO MARK, TURN THE THUMBSCREW

COUNTERCLOCKWISE (WHEN

FACING IT)

‘UP AND AWAY’

TO MOVE POINTER DOWN BELOW

THE ZERO MARK, TURN THE

THUMBSCREW CLOCKWISE (WHEN

FACING IT)

‘DOWN TO EARTH’

*MEASURING – MOVE LARGEST

MASS FIRST

HOW MUCH MASS WOULD AN

OBJECT HAVE IN OUTER SPACE?

TRICK QUESTION!

An astronaut is made of the same

types of atoms, and the same number

of atoms, both on earth and in space,

so the astronaut’s mass is the same in

both places!!!

THE DIFFERENCE

BETWEEN

MASS & WEIGHT

An object’s WEIGHT depends

on its MASS and the strength

of the GRAVITY pulling on it:

GRAVITY is the attractive force between 2 objects.

ALL OBJECTS with mass have a force of gravity: is

dependant upon the mass of two objects and the

distance between Jupiter has

more mass

than Earth;

Therefore

it has more

gravity

An object’s WEIGHT depends

on its MASS and the strength

of the GRAVITY pulling on it:

On which planet would you have a GREATER

WEIGHT???is dependant upon the mass of two objects

and the distance between

Jupiter has

more mass

than Earth;

Therefore

it has more

gravity

Weight depends on MASS

AND GRAVITY:

The force of gravity between two objects is

dependent upon the mass of two objects and the

distance between them.

If the distance between the objects increases – the Force

of Gravity decreases.

The astronaut is farther from the center of

Earth than we are;

Therefore the planet is not pulling as hard

on the astronaut

as the person standing on the surface!

Weight depends on MASS

AND GRAVITY:

If the distance between the objects

increases – the Force of Gravity decreases.

Where would you WEIGH MORE: On Earth

or in space?

The astronaut is farther from the center of

Earth than we are;

Therefore the planet is not pulling as hard

on the astronaut

as the person standing on the surface!

So,What is Weight again?

Definition: Weight is the force of one object pressing on another.

Weight is dependent not only on an object’s mass, but also on the strength of the gravity that is pulling on it.

Without gravity there is NO WEIGHT

Mass ≠ Weight

Mass and Weight are NOT the same thing!

Mass: Amount of matter an object contains

Has inertia (resistance to a push/pull)

Weight (Force):

Dependant upon Gravity (mass is not)

Attraction between two objects

Can change if the objects change distance

or mass

When gravity pulls on

your mass,

the resulting force is

called “weight”!

Mass and Gravity = Weight

Small mass x same

pull = less weight Large mass x same pull =

more weight

Source of Gravity Source of Gravity

Weight really is a measurement of the gravitational

attraction between you and the earth.

Remember – Weight is a force measurement

Compare: Mass vs. Weight on

different planets:

Jupiter has more mass than the Earth

Therefore it has more gravity! Your same

mass would weigh more on Jupiter than on Earth!

Person on Earth

is 150 lbs!

Same person on

Jupiter is 354.6 lbs!!!

Why is this true? What is different

between Jupiter and Earth?

Q: Did the person’s MASS (amount

of matter that makes them

up) ever change?

Test of Gravity

Drop a paperclip and a pen at the

same time, from the same distance.

Observe which one fell faster – the

more massive or the less massive

one?

Galileo found that no matter how

large or small, the objects fell at

the same Velocity.

So at what rate do objects accelerate

due to Earth’s gravity?

Test of Gravity

Which one fell faster – the

more massive or the less

massive one?

Galileo found that no matter

how large or small, the

objects fell at the same

Velocity.

So at what rate do objects of

different masses accelerate

(fall) due to Earth’s gravity?

Wait a second!

Leaves and feathers

fall very slowly and even changes directions

So what makes the leaf and feather fall

differently than a cannon ball?

So will feathers and leaves always

fall slower than cannon balls?

Force = Mass x Acceleration

So how do we solve for

weight?

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mkg

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22

Weight = Mass x Gravity

Acceleration

Acceleration Rate of Earth’s

Gravitational Pull

Compare your weight on Earth to what is would

be on the Moon:

Discuss: Why does your weight change?

Discuss: Does your mass change as well?