Question

A person standing near the edge of the top of a building throws two balls $A$ and $B$. The ball $A$ is thrown vertically upwards and $B$ is thrown vertically downward with the same speed. The ball $A$ hits the ground with a speed $v_A$ and the ball $B$ hits the ground with a speed $v_B$. Then,

• A. $v_A>v_B$
• B. $v_A<v_B$
• C. $v_A=v_B$
• D. The relation between $v_A$ and $v_B$ depends on height of the building above the ground.

Answer 1

The correct option is C $v_A=v_B$

The given condition can be represented as shown in the figure


So, we can say that the net displacement in both the cases is same i.e. $h$
So, from the third equation of motion we have,
$v^2-u^2=2as=2ah$
Here, for both the cases, $u,a=g$ and $s=h$ are same
So, we can say that the final velocity of ball in both the cases will be same i.e. $v_A=v_B$