Question

Explain why pressure and surface tension are not vectors?

Answer 1

Pressure is a scalar quantity; it is a rank 0 tensor.

Pressure is defined as force per unit area i.e,

$P=\frac{F}{A}$

But we know that force is a vector quantity and so what makes pressure a scalar quantity is the fact that it is the component of force along the direction of area that is taken into account while defining pressure.

Thus, the direction of quantities involved remain fixed and pressure becomes a scalar quantity.

Same here in surface tension it is a scalar quantity and have direction but it does not follow law of vector just like electric current.