A stone is dropped from a height of 20 m.

(i) How long will it take to reach the ground?
(ii) What will be its speed when it hits the ground? (g = 10 m/s²)

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Solution

(i) s (distance) = 20m
u (initial velocity) = 0 m/s
a (acceleration due to gravity i.e., g) = 10m/s²
t (time) = ?
S = ut +1/2 gt²
20 = 0×t + ½ ×10 ×t²
20 = ½ ×10×t²
20×2 = 10t²
20×2 ×10 = t²
t² = 4
t = 2
Answer: time = 2 sec

(ii). v (final velocity) = ?
u (initial velocity) = 0 m/s
a (acceleration due to gravity i.e., g) = 10m/s²
t (time) = 2 sec
v = u + gt
= 0 + 10 × 2
= 20m/s
Answer: v = 20 m/s

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Similar questions

g = 10 m / s^{2}

1.A stone falls from a building and reaches the ground in 2.5 seconds latter . How high is the building?

2. A stone dropped from a height of 20meter

i) How long it will take to reach the ground.

ii)what will be it's speed when it hits the ground.

10 m / s

40 m

(t a k e g = 10 m / s^{2})

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