question_answer

From a building two balls A and B are thrown such that A is thrown upwards and B downwards (both vertically). If \[{{v}_{A}}\] and \[{{v}_{B}}\] are their respective velocities on reaching the ground, then

A) \[{{v}_{B}}>{{v}_{A}}\]                    

B) \[{{v}_{A}}={{v}_{B}}\]

C) \[{{v}_{A}}>{{v}_{B}}\]

D) their velocities depend on their masses.

Correct Answer: B

Solution :

Ball A is thrown upwards from the building. During its downward journey when it comes back to the point of throw, its speed is equal to the speed of throw. So, for the journey of both the balls from point4to5.                     We can apply \[{{\text{v}}^{\text{2}}}-{{\text{u}}^{\text{2}}}\text{=2gh}\text{.}\] As u, g, h are same for both the balls, \[\,{{\text{v}}_{\text{A}}}\text{=}{{\text{v}}_{\text{B}}}\]