1. Scalar quantities are quantities which have magnitude only.
Examples of scalar quantities are mass, time, temperature, electric current, speed, volume, density, pressure, energy, power.
2. Vector quantities are quantities which have magnitude and direction.
Examples of vector quantities are displacement, velocity, acceleration, momentum, force.
3. Scalar quantities are added and subtracted in the same way as ordinary numbers are added and subtracted.
Example: 5 kg — 3 kg = 2 kg
4. Vector quantities are added and subtracted using parallelogram of vectors or triangle of vectors.
Example: A 3 N force is inclined at an angle of 30 degree to a 5 N force. They are added as follows:
The lengths of the arrows represent the magnitudes and
the directions of the arrows represent the directions of the forces respectively.
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