# Mass

MASS is a measure of the amount of matter in a body!

Mass is the quantity of matter in an object.

Mass is a scalar quanitity, that is it has no direction with it.

Mass is measured in grams or kilograms, (or in imperial units ounces, pounds, etc.) The amount of matter in a body does not change (unless some part of the body is removed).

The Mass of _____ is _______

The Mass of _____ is _______

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In the formula for force you see m for mass.

Weight is often confused with mass,

we get the butcher to weigh out our meat, he gives us an answer in kilograms (or pounds).

This is what causes the usual confusion between mass and weight.

A video on Mass,

Back 2 Measurement

Air has mass Weighing air

On a simple scale a 3 L bottle, with a valve in the lid

is balanced by a counter weight.

Air is pumped into the bottle until the pressure is doubled.

The bottle is then heavier.

A small extra weight (3.6 g) is used to restore equilibrium.

Rory Geoghegan UCD: for IOP Frontiers in Physics, 27/09/2008,

In the physics realm, we see weight is a Force, looking at the equation below, force is the product of mass and an acceleration!

What causes this acceleration ? Why do objects fall ? Gravity, g so