The speed of an object does not require a direction to be considered, it simply has a value and unit, for example, 27 \(m\,s^{-1}\). Velocity is a vector quantity which requires a value, unit and ...

gradient = \(\frac{change~in~y}{change~in~x} = \frac{change~in~speed}{change~in~time} = \) \( \frac{change~in~metres~per~second}{change~in~seconds}\) = metres per ...

This is a classic introductory physics problem. Basically, you have a cart on a frictionless track (call this m 1) with a string that runs over a pulley to another mass hanging below (call this m 2).