Question

A body free falling from rest has velocity v after it falls down a height H.The distance it has to fall down for its velocity to become double is A)2H or B)4H or C)6H or D)8H

Answer 1

sending you written solution

Answer 2

The velocity after falling a height 'H' is given by

v = √2gH

PROOF:

From laws of motion,

v² - u² = 2gH

v² = 2gH (∵ it falls from rest, u=0)

v = √2gH

So, if the velocity after falling some height 'l' is 2v, then

→ 2v = √2gl

squaring on both sides,

→ 4v² = 2gl

→ 4(2gH) = 2gl

→ 4H = l

Therefore, the body has to fall from a height of 4H to have a velocity of 2v after falling.

Hope it helps!