Transcript Standard EPS Shell Presentation

Learning Goals
Explain the meaning of mass and
describe the units for measuring mass.
Distinguish between mass and weight.
Define volume and explain how the
volume of matter is measured.
Measuring Mass and Volume
Key Question:
How do you measure mass and volume?
Measuring mass
Mass describes the amount
of matter in an object.
The SI unit for mass is the
kilogram (kg).
The kilogram is too large a
unit to be convenient for
small masses.
One gram (g) is one-thousandth of a kilogram.
What is the estimated mass of ONE zinc nut?
Matter
Matter is anything
that has mass and
takes up space.
All matter has mass.
Steel, plastic, rubber,
and glass are
different kinds of
matter.
A car has a lot more of each
kind of matter than a bike.
Mass and weight are different
 We tend to use the terms mass and
weight interchangeably, but they are
not the same thing.
 Mass is the amount of matter in an
object.
 Weight is a measure of the pulling
force of gravity on an object.
Mass and weight are different
 A 2.3 kg bag of
flour has a mass of
2.3 kilograms no
matter where it is
in the universe.
 The weight of the
bag of flour is less
on the moon.
The 5 lb bag of flour
on Earth weighs only
.8 lbs on the moon!
Volume
Volume is the amount of space an object
takes up.
The fundamental unit of volume in SI
is the cubic meter (m3).
More convenient smaller units are
cubic centimeters (cc or cm3), liters
(L) and milliliters (mL).
Volume
Measuring the
volume of liquids
is easy.
Pour the liquid
into a graduated
cylinder and read
the meniscus at
eye level.
Displacement
You can find the
volume of an irregular
shape using a
technique called
displacement.
Put the irregularly
shaped object in water
and measuring the
amount of water
displaced.
Comparing mass
and volume
Mass and volume are two
different properties of
matter.
Size does not always
indicate an object’s mass!
How the matter is packed
into space is more
important.
Learning Goals
Define density in terms of mass and
volume.
Identify units used to express the
density of materials.
Apply the density formula to solve
problems.
Density
Key Question:
How is an object’s density
related to its volume,
mass, and tendency to
sink or float?
Density
Density describes how much mass is
in a given volume of a material.
Density
Solids, liquids and
gases are matter, so
they all have density.
The density of water
is about one gram per
cubic centimeter.
Density
The units used
for density
depend on
whether the
substance is
solid or liquid.
 For liquids use
units of grams
per milliliter
(g/mL)
 For solids use
density in units
of g/cm3 or
kg/m3.
Density of common materials
Density is a property of material
independent of quantity or shape.
Density of common materials
Liquids tend to be
less dense than
solids of the same
material.
 Ex. solder (“sodder)
2.2 Density of common materials
Water is an exception to this rule.
The density of solid water (ice) is less
than the density of liquid water.
Determining Density
 To find the density of a
material, you need to
know the mass and
volume of a solid sample
of the material.
1. Mass is measured with a
balance or scale.
2. Use the displacement
method or calculate the
volume.
Density
Density changes for different substances
because:
1. Atoms have different masses.
2. Atoms may be “packed” tightly or loosely.
Solving Problems
Calculating Density
1. Looking for:
 …the density of the candle
2. Given:
 …mass = 1500 g; volume = 1700 mL
3. Relationship:
 D = m/V
4. Solution:
 1,500 g ÷ 1,700 mL = 0.8823529 g/mL
# Sig. fig = .88 g/mL