### Re: Tensor

The query and its answer may be of general interest.

Physical quantities can be scalars, vectors or tensors. Scalars are just numbers. Vectors have magnitude, direction and they follow certain law of addition. The third category is called tensor. If a quantity has magnitude but does not have direction of its own but its value depends on the direction, then it belongs to the category of tensors. For example, moment of inertia of a solid sphere is 2/5 MR^2 about an axis passing through its centre. However, it is 7/5 MR^2 about an axis along its tangent. In fact it can take many values depending upon the choice of axis. So, moment of inertia depends upon the direction, but it does not direction of its own. Hence it is a tensor. Note that the tensor algebra is beyond IIT-JEE and you will not hear about it often.

________________________________________
Sir,

Sub: tensors.

In the physics lesson SCALARS AND VECTORS, there is a term given as TENSORS.
It is described as the physical quantity which has no direction but value changes w.r.t direction.