JAMB - Physics (2015 - No. 33)

If a ball released from a height of 20m, How long would it take the ball to reach the ground? (assures g = 10m/s)
2sec
3sec
35sec
2.4sec

Explanation

Using the equation

S = ut + ½ gt2

H = s = 20m, t = ?

G =10m/s2, u = 0m/s

20 = 0 × t × ½ × 10 t

20 = 5t

i.e 5t2 = 20

t = 20/5 = 4

t = 4 (squaring both sides)

√ t2 = √4

= 2sec

∴ t = 2sec

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