The ball is thrown vertically upwards from a point located at a height of 5 m. Determine the time

The ball is thrown vertically upwards from a point located at a height of 5 m. Determine the time of flight of the ball, if it flew before the moment of falling the path equal to 15 m. Neglect the air resistance.

Let the maximum lifting height of the ball relative to the ground be N.

From the condition of the problem: 2H – 5 = 15, whence H = 10 m.

The height of the ball rise to the highest point of the trajectory:

h = g t1 ^ 2/2,

where g is the acceleration due to gravity, g = 9.8 m / s2.

On the other hand:

h = H – 5 = (10 – 5) = 5 m,

whence the time of lifting the ball:

t1 = (2 h / g) ^ 1/2 = (2 × 5 / 9.8) ^ 1/2 = 1.01 s.

Ball drop time:

t2 = (2 H / g) ^ 1/2 = (2 × 10 / 9.8) ^ 1/2 = 1.43 s.

Total flight time of the ball:

t = t1 + t2 = 1.01 + 1.43 = 2.44 s.