The formula of average velocity involves total displacement and total time taken for that displacement. For a stationary gas the average speed of its molecules can be in the order of thousands of kmhr even though the average velocity of its molecules is zero. V Q Ad t A v.
Calculating this velocity is a simple task.
If and only if the acceleration is constant the average velocity is the same as the average of the final velocity and the initial velocity. In this case of the teachers motion there is a. BarvfracDelta xDelta tfracx_f-x_0t_f-t_0 Where Delta V is the average velocity Delta x is the displacement Delta t is the total time. As we worked out above it ends up traveling at a final velocity v f of 15 ms.