A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate:
(i) The maximum height to which it rises.
(ii) The total time it takes to return to the surface of the earth.
(i) The value of acceleration due to gravity g will be taken as negative as the ball is going upwards.
Given,
Initial velocity of ball, u = 49 m/s
Final velocity of ball, v = 0 (As the ball stops at top)
Acceleration due to gravity, g = - 9.8 m/s2
Height, h =?
We know that,
v2 = u2 + 2gh
(0)2 = (49)2 + 2 × (-9.8) × h
0 = 2401 – 19.6 h
19.6 h = 2401
h = 
= 122.5 m
(ii) Now, we will calculate the time taken by the ball to reach at the highest point:
Given,
Final velocity, v = 0 (As the ball stops at top)
Initial velocity, u = 49 m/s
Acceleration due to gravity, g = - 9.8 m/s2
Time taken, t =?
0 = 49 + (-9.8) × t
0 = 49 – 9.8 t
9.8 t = 49
t = 
t = 5 s
The ball will take equal time to return to the surface of earth.
Therefore, Total time = 5 + 5
= 10 seconds