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Motion in one dimension

Scalar and vector quantites

Do you know what a physical quantity is? A physical quantity is any physical property that can be expressed in numbers. For example, time is a physical quantity as it can be expressed in numbers, but beauty is not as it cannot be expressed in numbers.

Scalar Quantities

  • If a physical quantity can be completely described only by its magnitude, then it is a scalar quantity. To measure the mass of an object, we only have to know how much matter is present in the object. Therefore, mass of an object is a physical quantity that only requires magnitude to be expressed. Therefore, we say that mass is a scalar quantity.

  • Some more examples of scalar quantities are time, area, volume, and energy.

  • We can add scalar quantities by simple arithmetic means.

  • It is difficult to plot scalar quantities on a graph.

Vector Quantities

  • There are some physical quantities that cannot be completely described only by their magnitudes. These physical quantities require direction along with magnitude. For example, if we consider force, then along with the magnitude of the force, we also have to know the direction along which the force is applied. Therefore, to describe a force, we require both its magnitude and direction. This type of physical quantity is called a vector quantity.

Therefore, we can define vector quantity as the physical quantity that requires both magnitude and direction to be described.

  • Some examples of vector quantities are velocity, force,…

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