\.{a}The command \.{a} is used to place a dot accent over the letter 'a' in mathematical expressions. This is often used to denote derivatives with respect to time, such as velocity or acceleration in physics.
Indicating the time derivative of a variable 'a'.
\text{\.{a} is the time derivative of a}Using a dot over 'x' to denote velocity, the first derivative of position with respect to time.
\text{\.{x} represents velocity}Using a dot over 'y' to denote acceleration, the second derivative of position with respect to time.
\text{\.{y} is the acceleration}