Question

a stone is released from the top of the building of height 20m calculate (a) the total time to return to the surface of the earth (b) its final veocity just before toching the ground

Answer 1

Answer:

(A)Initial velocity of the stone, u = 0

Final velocity of the stone, v = ?

Height of the tower, h = 19.6 m

Acceleration due to gravity, g = 9.8 ms-2

For a freely falling body:

v2 - u2 = 2 g h

v2 - 02 = 2 × 9.8 × 19.6

v2 = 19.6 × 19.6 = (19.6)2  

v2 = 384.16

v = 19.6 ms-1

Hence, the velocity of the stone just before touching the ground is 19.6 ms-1.

Concept Note: When a body is falling vertically downwards, its velocity increases, so the acceleration due to gravity g is taken as positive.

 

Explanation:

Answer 2

Answer:

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