IGCSE Physics

Measuring Mass

Weight is the force of gravity acting on a mass.

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Weight (N) = mass (kg)  x 10

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Compare between mass and weight

Quantity	Definition	Unit	Device
Mass	the amount of material that a body containsit doesn’t change from one place to another	Kg	Beam balance
Weight	the force of gravity acting on a massit changes from one place to another according to the strength of gravity of this place	N	Spring balance

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Notes:

• Mass and weight are not the same.
• Weight will be discussed later.

• Moon’s gravity is 1/6 of the gravity of earth.
• If a man with mass 120 kg.
• His weight on earth will be 1200 N.
• His weight on moon will be 200 N.
• His weight in space will be zero N.

Notes about measuring small masses:-

a)   On measuring the mass of very small objects like pins or similar, measure the mass of a certain number of them (40 for example) and then divide the mass of them on this certain number to reduce the measurement error.

b)   As you increase the number the error will be reduced more.

Important note:-

High mass means “High INERTIA”…. what is inertia?