Measuring Matter:
Mass, Weight and Volume
309-1 describe qualitatively the relationship
between mass and weight
Using fluids requires that we
understand their behavior.
You need to know how they act when
they are still and moving, when
something is moving in them and
when they are being pushed and
pulled.
Mass and Weight
• How much do you weigh?
• When we talk about weight, we
usually mean mass. Mass and
weight are not the same thing.
Mass – Mass is the amount of matter in an object
(g, pounds, kg)
Weight – Weight is the measure of the force of gravity
pulling on an object (newtons, N)
In order to understand the difference between mass
and weight, remember that the pull of gravity acts on
all objects on Earth, keeping people and objects from
floating away. Gravity is not the same everywhere in
the universe, so your weight is different here than on
the moon.
The force of gravity causes things to fall “down”
toward the centre of the Earth.
Weight being a force, is measured in newtons (N),
named after Sir Isaac Newton.
Why does the weight of an
object change?
The weight of an object changes because
gravitational pull in the universe is not the same.
*On Earth the gravitational pull is 9.81 m/s2
*On the moon the gravitational pull is 1.62 m/s2
Volume
• Matter has mass and weight, but it also takes up
space. Volume is a measure of the amount of
space occupied by matter.
• Volume is measured in cubic meters (m3), liters
(L), cubic centimeters (cm3) or milliliters (mL).
• Liquids are measured by observing how much of
a container they fill.
• Rectangular solids may be measured with a ruler,
and their volume calculated using the formula
• Volume = length x width x height
How are liquids measured?
Liquids are measured by observing how much of a
container a liquid fills
The volume of irregular solids can be measured by
displacement, using the formula
Volume of an object =
(volume of water + object) – (volume of water)
Displacement: Is a technique used to measure
the volume of small irregular solids
Explain how displacement
works.
Choose a container that a small object will fit in.
Pour water into the empty container until it is half
full. Record the volume of water in the container,
then carefully add the object. Record the volume
of water plus the object.
Understanding Concepts
Describe the relationship
between mass and weight. Give
an example.
The measurement of mass for an object remains constant
everywhere in the universe, provided nothing is taken away
form the object or added to it.
The measurement of weight for an object changes as
the force of gravity acting on the object changes.
Weight will be greater where the
force of gravity acting on the object
is greater.
For example, an object on Earth has the
same mass as an object on the Moon, but a
greater weight when on Earth than on the
Moon. ( The Moon’s force of gravity is
approximately one sixth that of Earth’s)
Imagine you have travelled to a planet that has
twice the force of gravity of Earth. You have taken
a solid with a mass of 1kg with you. Describe its
mass, weight, and volume on this planet, compared
with that on Earth.
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The mass of the solid remains the same, its weight increases
two-fold, and its volume remains the same.