question_answer

A body freely falling from the rest has a velocity ?v? after it falls through a height ?h?. The distance it has to fall down for its velocity to become double, is                 [BHU 1999]

A)             \[2h\]   

B)             \[4h\]

C)             \[6h\]   

D)             \[8h\]

Correct Answer: B

Solution :

                Let at point A initial velocity of body is equal to zero for path AB : \[{{v}^{2}}=0+2gh\] ?(i) for path AC : \[{{(2v)}^{2}}=0+2gx\]                        \[4{{v}^{2}}=2gx\]  ?(ii)    Solving (i) and (ii) \[x=4h\]