# Scalar and vector quantities

Scalars are quantities that have magnitude only; they are independent of direction.

Vectors have both magnitude and direction. The length of a vector represents magnitude. The arrow shows direction.

### Scalars - Vectors - TENSORS

R. Chennamsetti, Scientist, R&D Engineers, India

Just to add these, scalars are zeroth order tensors and vectors are first order tensors.

Regards,

- Ramdas

### tensor

then you have to teach students what is a tensor (they are 1st year undergraduate), this definition is not straightforward.

### what is tensor?

Obviously, the mathematic definaton of the tensor could be very complex for the engineering students. Is there any defination easy to understand?

BTW: The tensor class taught by Q.S. Zheng is very interesting and favorable. However, the lectures are written in  Chinese. Is there anybody could supply an English versions or other materials for the people here to know the tensor, it may be useful for others.

Lee

### Right!!

R. Chennamsetti, Scientist, R&D Engineers, India

Exactly. That makes their understanding more complicated...

Regards,

- Ramdas

### It could be sais that a

It could be sais that a tensor is a physical entity that needs one or more values (component) to be completely and properly defined: That is to say, it could need just one value to define a scalar which is a zero order tensor, three for a vector which is a second order tensor, nine for a second order tensor (the quantity that the name came from when defining the mechanical stress) and so on. On the other hand, to be a tensor it is also necessary that its components change or transform following certain rules when expressed in different coordinate system (Rule of quotient).

Regards,

Carlos

Un tensor es una cantidad física que requiere una o más componentes para estar completamente definida: Solo un valor para un escalar que es un tensor de orden cero, tres para un vector (tensor de primer orden), nueve para un tensor de segundo orden (el nombre fue tomado del tensor de tensión), etc. Además, cuando el tensor es de primer orden o superior, sus componentes deben transformarse siguiendo determinadas reglas (Ley del Cociente) cuando son expresadas en diferentes sistemas de coordenadas.

Saludos,

Carlos