What are scalar quantities?

• Scalar quantities  are  the physical quantities that only  have a size or magnitude .
• No other information is needed   to specify them further.
• Scalar quantities do not have directions

Examples of scalar quantities?

• Volume, density, speed, energy, mass,  length,and time.

Let us understand why the above are the examples of scalar quantities.For this we shall take a few examples.

• Length: If you wish to state the length  of a pencil, then it is enough to say that its length is 13 cm. You do not have to state its length as 13cm east  or 13 cm west etc. The length of the pencil is 13 cm is a  complete piece of information  needed to describe the length.
• Mass: The mass of the box is 20kg is again an information that is completely needed to describe the mass of the box. The mass will stay the same irrespective of the direction, so direction need not be stated to describe the mass of the box. Hence mass is a scalar quantity.
• Time: Time again is a scalar quantity. You tell someone that the time is 3pm and he sure wont ask you anything more about the time. This piece of information tells all about the time.
• Energy:   For instance 1300Joules of energy is a complete information about energy. You do not need to specify the direction of thus energy. So energy is a scalar quantity.
• Speed: You tell a person that you are driving 100km/h and the person is sure to understand everything needed about the speed of the car. There is absolutely no need of stating the direction of the  speed.
• Volume: If a box has a volume of  25 cm³, then its clear that it can hold no more than  25 cm³. This is complete information and hence  volume is a scalar quantity.