Question

why can velocity and speed be interchanged in the formulas

Answer 1

the rate of change in the position of an object as it moves in a particular direction
is called velocity; it gives you both direction and magnitude. The rate of movement irrespective of direction is called speed; It is equal either to distance traveled divided by travel time, or to rate of change of distance with respect to time.

Answer 2

CAUSE BOTH HAVE SAME PHYSICAL ASPECT..!!!AND MAKE SAME CHANGES IN IN ANY SYSTEM..!!

Answer 3

Alas, they cannot always be exchanged. There are times when a vector--such as velocity--is required.