Question

Three stones $A,B$ and $C$ are simultaneously projected from same point with same speed. $A$ is thrown upwards, $B$ is thrown horizontally and $C$ is thrown downwards from a building. When the distance between stone $A$ and $C$ becomes $10m$, then distance between $A$ and $B$ will be

• A. $10m$
• B. $5m$
• C. $5\sqrt{2}m$
• D. $10\sqrt{2}m$

Answer 1

Answer: (C)

Let the stones be projected at $t=0\sec$ with a speed $u$ from point $O$. Then an observer, at rest at $t=0$ and having constant acceleration equal to acceleration due to gravity, shall observe the three stones move with constant velocity as shown.
In the given time each ball shall travel a distance $5$ metre as seen by this observer. Hence the required distance between $A$ and $B$ will be
$=\sqrt{5^2+5^2}=5\sqrt{2}$ metre