How much is the height of a person? How tall is a building? What is the duration of a day? What is the weight of a person? What is the temperature of a city? There is a similarity amongst the answers of all these questions. The answers are all scalar quantities. Physics offers many types of measurements – one of them is scalar quantities and the other popular one is vector quantities.
Scalar quantity can be defined as the quantity which can be measured just by its magnitude. The unit of measurement is necessary though. Like number 10 in itself is not a scalar quantity but 10 kilometers is. A scalar quantity does not need any extra attribute to define or explain it. There is no need for a directional dimension to be added to it. Scalar quantities do not tell anything about direction of the object. Example a person covers 10 kilometers distance, but the distance covered was in North, South, East or West direction, is not specified.
EXAMPLES OF SCALAR QUANTITY
Length: The units include centimeter, meter, kilometers and all the smaller or larger magnitudes.
Time: 1 second, 1 minute, 1 hour, 1 day, 1 month, 1 year, 1 fortnight, 1 millisecond are all scalar quantities. I spend 10 minutes to walk around the building. But which direction I walked in is unclear.
Volume or weight: The mass of the medium is also a scalar quantity. Any quantity that measures the mass and not the direction is scalar. Like grams, kilograms, ounce, pound, tons etc.
Temperature: The degree of hotness or coldness is scalar as well. Example: 100 degrees Celsius or 35 degrees Fahrenheit.
Speed: The pace at which object moves is scalar. Like 10 kilometers per hour or 5 meters per second. It is scalar as long as it is not associated with the person’s direction of travel.
Energy: This is measured in Joule, Kilojoules and any other similar larger or smaller magnitude.
Work: The force applied to move an object by some distance is what we call work in Physics. The quantity used to measure this force is Joule (same as energy). With this, we don’t know, in which direction the force was applied to move the object. It can be any direction.
Power – Power is the rate of doing work. The unit of measurement of power is Watt (Joules per second). It has up and down measurement units like Kilowatt or GigaWatt.