Notes on Isaac Newton
MATTER
Matter –
 The substance that all physical objects are made
 Is anything that has mass and takes up space (volume)
 The amount of matter in an object is its MASS
MASS The amount of matter in an object
 Finding mass is like counting the number of atoms …BUT…impossible to do so
 SO….HOW DO WE FIND MASS?
 We find MASS on a BALANCE (a type of scale)
 We measure MASS in units called GRAMS
 Example:
o If a bowling ball has 1000 grams of mass, its like saying it has the same number of atoms
as 1000 grams of water, or 1000 grams of gold, or 1000 grams of chips!
Isaac Newton
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Q.
A.
Noted for his experiments with light (found that white light contains all the colors of the
spectrum)
He wrote Principia Mathematica – our earliest introduction to gravity, optics (light) , calculus
and physics
Said that all atoms have mass, volume and inertia
What is inertia?
An object’s resistance to a change in motion
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Q.
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Theorized that all matter has GRAVITY
GRAVITY is an invisible force that attracts all matter to all other matter
It takes TWO to GRAVITY –i.e. gravity happens between TWO OR MORE objects
What determines the amount of gravity?
The amount of MASS
Inertia
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Inertia says that an object in motion wants to keep moving UNLESS another force acts on it.
Example A bowling ball will stay in one place forever unless some force pushes or pulls on it
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Example A moving bowling ball will just keep going until some force stops it
Inertia is determined by MASS – the number of atoms
The more atoms or mass in an object means more inertia
The more atoms an object has also means the more gravity acting on that object
Side-note:
Higgs Boson – a scientist who theorizes that every atom has a particle called the Higgs
Boson where we think that mass comes from…sometimes called the “God Particle” because it points
toward the creation of mass.
Gravity - an invisible and weak force between atoms that attracts all matter to all other matter
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Every atom has gravity which means that the more atoms an object has the more gravity acting
on it
So what else affects gravity??? (The sun has more mass than the Earth. Why then doesn’t the
earth get pulled towards the sun?)
Newton determined that the amount of gravity acting on objects depends on TWO things:
Number 1 is MASS and number 2 is DISTANCE between the object
Mass is directly proportional to gravity – double the mass of an object and you double the
gravity
Distance in inversely proportional to gravity – if distance increases, gravity decreases
This means the closer 2 objects are together, the greater the gravity AND the farther away 2
objects are from each other, the weaker the gravity
Law of Universal Gravity
Every object in the universe attracts every other object with a force directed along the line of center
of the two objects that is proportional to the product of their masses and inversely proportional to the square
of the separation between the two objects.
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Q.
How do we measure gravity?
Newton actually came up with a formula to QUANTIFY/measure gravity……………
Fg = G m1 m2 ….Fg = force of gravity G= universal gravitational constant
r squared
r squared = the distance between squared
What would gravity be like on the moon?
- Say you weigh 120 pounds on Earth
- The moon is about 1/6 the mass of Earth……so…
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Would your mass change
NO! Mass (the number of atoms) stays the same
Would your weight change?
Yes! You would weigh 1/6 your weight on earth
Things weigh 6 x less and fall 6x slower on the moon than on Earth
Things do NOT float on the moon – they just fall 6x slower than on Earth
Q.
A.
What is the actual difference between mass and weight?
Mass is the matter (number of atoms) in an object and weight is the force of gravity acting on
an object - the more mass an object has, the greater the gravitational force acting on it. The
closer two object are, the greater the gravitational force
Mars is about 80% the mass of Earth
Q. What would you weigh on Mars?
A. Well…if you weigh 100 pounds on Earth and Mars is 80% the mass of Earth, you would weigh 20
% less on Mars or about 80 pounds
Mass
Weight
Is the amount of matter (atoms) in an object
Is the amount of gravity between two
objects
Is measured on a balance
Is measured on a scale
Is measure in units called grams
Is measured in units called newtons
Distance – the linear size between 2 points
Dimensions – we live in a 3 dimensional world – (LWH)
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One dimensional – distance for point q to point B – a straight line
Two dimensional – can travel in 2 directions – left and right . This gives us AREA = LW
Three dimensional – Can travel in 3 directions – multiple planes stack up. This gives us AREA
= LWH
Euclid asked the question – how do I measure 3 dimensional objects
He called one length, one width and one height can came up with the formula V = L W H
Volume = the total space filled by an object (3 directions)- LWH
Area = the flat surface covered in 2 directions (LW)