Neco 2020 Physics Question 30

A particle moves along a straight line with the velocity-time graph described below: \(\bullet\) From \(t=0\) to \(t=2\;\text{s}\), velocity increases uniformly from \(0\) to \(8\;\text{m s}^{-1}\). \(\bullet\) From \(t=2\) to \(t=5\;\text{s}\), velocity remains constant at \(8\;\text{m s}^{-1}\). \(\bullet\) From \(t=5\) to \(t=7\;\text{s}\), velocity decreases uniformly to \(-4\;\text{m s}^{-1}\). \(\bullet\) From \(t=7\) to \(t=9\;\text{s}\), velocity remains constant at \(-4\;\text{m s}^{-1}\). Determine (a) the total displacement of the particle over the 9 s interval, (b) the magnitude of its average speed, and (c) the instant at which the particle changes direction.