If a ball released from a height of 20m, How long would it take the ball to reach the ground? (assures g = 10m/s)
-
A.
2sec -
B.
3sec -
C.
35sec -
D.
2.4sec
Correct Answer: Option A
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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