Question

Balls $A$ and $B$ are thrown from two points lying on the same horizontal plane separated by a distance $120m$. Which of the following statement(s) is (are) correct

• A. The ball can never meet
• B. The balls can meet if the ball $B$ is thrown $1s$ later
• C. The balls can meet if the balls are thrown at the same time
• D. The two balls meet at a height of $45m$ if thrown simultaneously.

Answer 1

Answer: (C), (D)

The correct options are
C The balls can meet if the balls are thrown at the same time
D The two balls meet at a height of $45m$ if thrown simultaneously.

They can meet only if they reach the top point of A simultaneously.

The top point will be at height $h=\frac{u^{2}si{n}^2\theta }{2g}=\frac{2500\times 9}{20\times 25}=45m$ and time taken by A to reach the top point will be $t=\frac{usin\theta }{g}=\frac{50\times 3}{10\times 5}=3s$

The time taken by B to reach the top point of the path of A will be given by $h=ut-g{t}^2/2$

or $45=30t-5t^2$ which gives $t=3s$

So both $A$ and $B$ are reaching there simultaneously provided they are thrown at the same time.

options C and D are correct.