Matter

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Matter…

• Makes up all of the objects and living organisms in the universe

• Anything that has mass AND takes up space• Light and sound are NOT matter…why?

– Matter is made of particles called atoms…matter IS atoms.

– Atoms have mass– Air is made of atoms– Sound and light waves traveling through air do not

have mass OR take up space

Three (of five) forms of Matter:

• Solid matter - has a fixed volume and shape of the object or substance.

• Liquid matter - has a definite volume but not a definite shape.

• Gas matter - does not have a definite shape and volume.

Mass…• A physical property of matter• Measure of how much matter an object contains• Standard unit: Kilogram (kg)

– 1 kg = 1000 grams (g)

– Ex: grapefruit: 500 g, penny: 2-3 g

• Measure mass using a triple-beam balance

Mass vs Weight

Mass is a measurement of the amount of matter something contains

Weight is the measurement of the pull of gravity on an object.

Mass is measured by using a balance comparing a known amount of matter to an unknown amount of matter.

Weight is measured on a scale.

The Mass of an object doesn't change when an object's location changes.

Weight does change with location.

• A triple beam balance compares a known mass to an unknown mass, so it is unaffected by gravity.

• A scale measures weight, the triple beam balance gives a true measure of mass.

• On the moon the mass on the left side of the balance may 'exert less force', but then less force will be needed to balance it.

Weight and Gravity

• Recall…• Gravity is the force that pulls two masses toward

each other• Standard unit: Newton (N)

– Common unit: Pound (lb)

• Force = mass * acceleration (F=ma)– Newton = kilogram*meter/second^2 (N = kg m/s2)

• Weight is a force!– Mass is amount of matter of an object, weight is how

strongly gravity is pulling on that matter

F = G[M m/r2]

• What will cause the force of attraction to increase or decrease? – If either mass increases the force of attraction increases

proportionally. Since the moon has 1/6 the mass of earth, it would exert a force on an object that is 1/6 that on earth.

• Why is the 1/r2 factor so important? – This is an inverse square relationship which seems to show up a lot in

physics. How does it affect the force?– When r=1 the value 1/r 2 is 1.0, but at r=10 it deceases to 1/100. That

means gravity gets weak 'quick' as we move away from the earth.

Compute Mass and Weight

• If a cube has a mass of 90.91 kilograms and a weight of 200 pounds on Earth, what will its mass and weight be on another planet?– The Moon has a gravity that is 0.165 of Earth's.

The cube will have a weight of________________ pounds

and a mass of

_______________ kilograms

– Jupiter has a gravity that is 2.34 times greater than Earth's…weight? Mass?

Compute Mass and Weight

• On the moon:– Weight = 33 lb– Mass = still 90.91 kg!

• On Jupiter– Weight = 468 lb– Mass = 90.91 kg

Volume

• Volume is the amount of space an object occupies. • The volume of an object can be calculated

geometrically using mathematical equations or by measuring liquid displacement.

• Measure the volume of a cube using the formula V=(side)x(side)x(side) (length times width times height) and by using a graduated cylinder to measure liquid displacement.

• Volume = L x W x H (cm3 or in3 etc.) • The side of the cube is approximately 3.1 centimeters.

How many inches does this convert to (use 2.54 cm. = 1 inch)?

Measure Volume by Displacement• What was the amount of water displaced by the

object? (1 ml = 1cm3)

                                Before                                                After

Density

• Each box has the same volume.

• If each ball has the same mass, which box would weigh more? Why?

Density• The box that has more balls has more mass per

unit of volume. D = m/V• The density of a material helps to distinguish it

from other materials. • Mass: grams (g) or kilograms (kg)• Volume: cubic centimeters (cm3) or cubic meters

(m3)• Density: grams/cubic centimeter (g/cm3) or

kilograms/cubic meter (kg/m3)

Periodic Table masses:One gram is about 600,000,000,000,000,000,000,000 amu (a 6 followed by 23 zeros) = 6 x 1023 amu.

Periodic Table masses:One gram is about 600,000,000,000,000,000,000,000 amu (a 6 followed by 23 zeros) = 6 x 1023 amu.

Density of a Liquid

• Problem: You are given two unknown liquids. Find the density of each. Materials: 100ml graduated cylinder, triple beam balance, calculator, 2 unknown liquids.

• Procedure: • 1) Find the mass of the empty graduated cylinder. • 2) Pour unknown liquid #1 into the graduated cylinder to

the 50 ml. level. • 3) Find the mass of the graduated cylinder with 50ml of

unknown liquid #1. • 4) Repeat steps 1-3 for unknown liquid #2.

Density of a Liquid

• Liquid #1:• Given: Mass of empty

graduated cylinder = 78 grams• Mass of graduated cylinder

with unknown liquid #1= 128 grams.

• Find:• a) Mass of just the liquid =

____ b) Volume of liquid=_____c) Density of liquid #1 =____

• Liquid #2:• Given: Mass of empty

graduated cylinder = 78 grams• Mass of graduated cylinder

with unknown liquid #2= 117.5 grams.

• Find:• a) Mass of just the liquid =

____ b) Volume of liquid =_____c) Density of liquid #2=____

What is the Liquid?• What is each liquid?

Using the table below it is now possible for you to determine what each liquid is.

• Densities for some common liquids are:

Substance Density (gm/cu.cm)

Water 1.00

Cooking oil 0.92

Sea Water 1.025

Carbon tetrachloride 1.58

Benzene 0.87

Glycerin 1.26

Methanol 0.79

Extension: Air Pressure

• Air pressure is the force exerted by the weight of a column of air above a particular location.

• Imagine a sealed container full of air

• Change the pressure– Increase the density of the air by either putting

more air molecules into the container or reducing the volume of the container.

• Therefore, changes in air pressure can come about by changes in air density

• Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of the air above that surface.

• If the number of air molecules above a surface increases, there are more molecules to exert a force on that surface and consequently, the pressure increases. •The opposite is also true, where a reduction in the number of air molecules above a surface will result in a decrease in pressure.

Air Pressure & Altitude• Air pressure decreases as one moves upward through

the atmosphere because the length of the column of air shortens and hence there is less mass above a given location.

• Because air is highly compressible, the air is closely packed together near the surface (high density) and less densely packed aloft