6Ea/5
Weight and mass
There are some words that we use in everyday
life that have a different meaning when we
use them in science. Words like weight and
kilograms are two of these words. Your weight
is the force of gravity pulling on you, and
it is measured in newtons. If you measure
something in kilograms, you are measuring
its mass.
My weight is 35
kilograms.
Weight and mass are two very different things:
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your mass is the amount of matter in you
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your weight is the force of gravity pulling
down on you.
In everyday life, the difference between weight and mass does not really matter, and it
would only be confusing if you went into a shop and asked for 1 newton of sweets!
The difference does matter if you think about going to the Moon. If your mass is 35 kg
on Earth, it would still be 35 kg if you went to the Moon because there is still the same
amount of matter in you. You can only change your mass by doing things like cutting
your hair, going to the toilet or eating. Your weight would change if you went to the
Moon, because the force of gravity on the Moon is less than the force of gravity on
the Earth.
?
1 a What does ‘mass’ mean?
b What are the units for mass?
2 a What does ‘weight’ mean?
b What are the units for weight?
3 What should the boy in the cartoon be saying to be correct?
4 a Why would your mass go up if you ate a big meal at tea time?
b Why would your mass go down again by about breakfast time?
5 If you went to the Moon:
a how would your mass change
b how would your weight change?
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knowledge, literacy
Exploring Science
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