A ball is thrown vertically upward from the edge of a school terrace that is 20m above the ground with an initial speed of 15m/s. Take g=10m/s2.
(i) Find the maximum height attained by the ball above the terrace.
(ii) Determine the greatest vertical height of the ball above the ground.
(iii) Calculate the time taken to reach the maximum height.
(iv) When the ball returns to the level of the terrace during its downward journey, what will be its speed?