1 Earth's gravity pulls all objects to its centre.
2 The weight of an object is a result of the force of gravity.
3 The weight of an object is not constant. It changes from one place to another, depending on the force of gravity acting on the object.
4 The weight of an object is greater at the poles than at the equator. This is because the force of gravity is greater at the poles.
5 The weight of an object can be measured using a spring balance. The length of the spring with an object is directly proportional to the force acting on it.
6 The SI unit for measuring weight is newton (N).
Spring Balance
7 The unit newton or kilogram-force is normally used in scientific investigations. One newton is almost equal to one tenth of a kilogram-force.
8 The compression balance can also be used to measure weight.
9 Before measuring an object, you must check that the spring indicator is at the zero mark.
What is Mass?
1 Mass is the quantity of matter contained in an object.
2 The mass of an object does not change because the quantity of matter contained in it is the same wherever the object is.
3 The lever balance or the beam balance is used to measure the mass of an object.
4 The lever balance is easier to use because the mass of the object can be read directly. With a beam balance, the mass of the object needs to be balanced with a standard mass. There are two scales on a lever balance. The first scale measures from 0 g to 250 g. The second scale measures from 0 g to 1 000 g.
5 The SI unit for mass is the kilogram (kg).
The Difference between Mass and Weight
1 Weight and mass are two different quantities.
2 The weight of an object depends on the Earth's gravitational pull. The greater the gravitational force, the greater the weight of the object.
3 The mass of an object is the amount of matter that it contains.
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