Which of the following is a vector quantity? A.20mph. B.30mph northwest. C.55 m/s. D.30milles

Explanation:

Vector quantities are those quantities which needs both magnitude and direction for their description.

Here, in all the options except option B, there is no direction. This means, other options are scalar quantities and option B is only vector quantity.

Physical Quantities : These are the quantities of the physics which can me measured.

There are two types of physical quantities,

Vector quantities are those quantities which needs both magnitude and direction for their description. Example : Velocity, acceleration etc.

Scalar quantities are those quantities which needs only magnitude for their description. Example : Speed , distance etc.

this is poiselle's equation from fluid mechanic in physics. mech eng