Question

A stone is dropped from a height of 20m , how long does it takes to reach the ground

Answer 1

Hey!

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Height (h)= 20m
Initial velocity (u) = 0
g = 9.8 m/s^2
t=?
v=?

v^2 - u^2 = 2as
v^2 -0 = 2×9.8×20
v^2 = 392
v= √392
v= 19.79


Using third equation of motion, we can find the answer,

v - u = at
19.79 = 9.8 × t
19.79/9.8 = t

t= 2.02

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Hope it helps...!!!

Answer 2

Answer: t = 2 s

Explanation: h = ut + 1/2 × 10×t2

20 = 0+1/2×10×t2

t2=4

T = 2s