Question

Tom and Dick are running forward with the same speed. They are throwing a rubber ball to each other at a constant speed v as seen by the thrower. According to Sam who is standing on the ground the speed of ball is

• A. same as v
• B. greater than v
• C. less than v
• D. None of these

Answer 1

Answer: (B)

Let $v_{BG}$ be the velocity of ball w.r.t. ground,
$v_{BT}$ be the velocity of ball w.r.t. thrower
and $v_{TG}$ be the velocity of thrower w.r.t. ground.
Then ${\vec{v}}_{BG}={\vec{v}}_{BT}+{\vec{v}}_{TG}$
Here, ${\vec{v}}_{TG}>0$
Therefore, velocity of the ball w.r.t. ground will be greater than velocity of ball w.r.t. thrower.