If a ball released from a height of 20m. How long would it take the ball to reach the ground? (assures g = 10m/s²)

A. 2sec
B. 3sec
C. 35sec
D. 2.4sec

Correct Answer:

Option A – 2sec

Explanation

Using the equation

S = ut + ½ gt²

H = s = 20m, t = ?

G =10m/s², u = 0m/s

20 = 0 × t × ½ × 10t²

20 = 5t²

i.e 5t² = 20

t² = 20/5 = 4

t = √4   = 2sec