The two measurements necessary for calculating average speed are…a. acceleration and time b. velocity and time c. distance and time d. distance and acceleratione. displacement and time

C. Distance and Time

Explanation:

Speed is defined as the distance covered per unit of time. It is a scalar quantity and as such expressed in scalar terms. When we talk about speed, the direction of motion does not matter. We only try to find the rate at which a body moves with time.

It is expressed as:

                        Speed =

The SI unit of speed is m/s or ms⁻¹

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.