A stone is thrown vertically upward with an initial speed of 20ms−1 from the roof of a building that is 25m above the ground. Neglect air resistance.
a. (i) Calculate the maximum height reached by the stone above the roof.
b. (ii) Find its speed when it is 10m above the roof while moving upward.
c. (iii) Determine its speed when it is again 10m above the roof on its way down.