Vocabulary
• Mass
• Weight
• Triple beam balance
• Riders
• Density
Mass
A measure of the
amount of matter an
object contains
Weight
A force that measures
the pull on a given
mass by gravity
Triple beam balance
An instrument used to
measure mass or weight by
balancing an object with
three counterweights
Riders
The three sliding
weights on the beams of
a triple beam balance
Density
The ratio of the mass of
an object to its volume
Mass
Density = Volume
Measuring Mass and
Weight
What tools and instruments do
we use to measure mass?
What units do we use when
measuring mass or weight?
Kilogram (kg), gram (g),
milligram (mg), tonnes (t),
for weight Newton (N)
Weight
The correct unit for force is
the Newton (=1kg m/s2)
Gravity makes a 1 kilogram
mass exert about 9.8 N of
force on Earth
Weight or Mass?
An object has
mass (say 100 kg).
This makes it
heavy enough to
weigh 100 kg
An objects weight is how
hard gravity is pulling on
it.
We think the weight is the
same everywhere ...
because we all live on the
surface of the planet Earth!
But in orbit it would not push on the scales at
all.The scales would show 0 kg ... but the mass
is still 100 kg !
An object's mass doesn't
change (unless you remove
some!), but its weight can
change.
Here are some conditions where the
Weight might change:
• in space (can be weightless!)
• on the moon (a 100 kg mass would
weigh 16.6 kg)
• you can even get very slight differences
in weight in different locations on earth!
Triple Beam Balance
Pan
Zero
Adjustment
Knob
Pointer and
Zero Mark
Riders
Beams
Triple beam balance is an instrument
used to measure mass of an object. It
functions by balancing an object with
three counterweights (the riders attached
to three beams) to accurately find the
object's weight.
Riders – The three sliding weights on the
beams
Beams – Three beams that hold the riders
Reading A Triple Beam Balance
224.6 g
Reading A Triple Beam Balance
216.6 g
Reading A Triple Beam Balance
133.0 g
Reading A Triple Beam Balance
488.7 g