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EASY READ Measurements

How do we measure mass and weight?

If you were able to stand on the Moon, you would weigh much less than you do on Earth. That is because weight is a measurement of how strongly gravity pulls on an object, and the Moon (which is a lot smaller than Earth) has lower gravity than Earth. However, your mass—the amount of matter you are made up from—would not change.

This astronaut weighs less on the Moon than he does on Earth
This astronaut weighs less on the Moon than he does on Earth

Mass

An elephant has a much greater mass than a rabbit
An elephant has a much greater mass than a rabbit

Mass is the amount of matter that something contains. A huge, heavy elephant has a much greater mass than a tiny, light rabbit.

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Two objects the same size can have different masses
Two objects the same size can have different masses

Two things that are the same size can have different masses. For example, a football and a bowling ball are the same size. But the football is hollow, so it has a lower mass than the bowling ball. The bowling ball, which is solid all the way through, contains more matter than a football—it has a greater mass.

Weight

When we measure the weight of something, we are actually measuring how strongly gravity pulls on it. There are two systems for measuring weight: metric measures and imperial measures. Most countries use the metric system, while the USA uses US customary units, which are similar to imperial measures.

The metric system measures weight using grams, kilograms and tonnes. There are 1000 grams (g) in 1 kilogram (kg). 1000 kilograms equal one tonne.

Lifting weights at the 2012 London Olympic Games
Lifting weights at the 2012 London Olympic Games

The imperial system and US customary system measures weight using ounces, pounds and tons. There are 16 ounces (oz) in a pound (lb). (In the imperial system, 14 pounds make up a stone.) A ton is made up of 2000 pounds in the US system (sometimes known as a “short ton”) or 2240 pounds in the imperial system (a “long ton”).

Key words

mass the amount of matter an object contains

weight a measurement of how strongly gravity pulls on an object
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pics

Balance scales allow us to compare the masses of two objects in the same gravity field (in this case, Earth's). When the cherries in the left-hand pan balance with the weights in the right-hand pan, the masses in the two pans are the same. Now we can add up the weights in the right hand pan and this gives us the "weight" of the cherries.
An elephant has a much greater mass than a rabbit.
This football and bowling ball are the same size, but have different masses. The football has a lesser mass than the bowling ball, because it is hollow. The bowling ball has a greater mass because it is solid all the way through, meaning there is more of it.
If you were able to stand on the Moon, you would weigh much less than what you do on Earth. This is because the Moon has lower gravity than Earth. If you weigh 40 kg on Earth you would weigh only 6.6 kg on the Moon.
Weight is a measurement of how strongly gravity pulls on a mass.

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