Question

From a fixed support,two small identical spheres are suspended by means of strings of length $1\, m$ each .They are pulled aside as shown and then released $B$ is the mean position.Then the two spheres collide.

• A. at $B$ after $0.25$ second
• B. at $B$ after $0.5$ second
• C. on the right side of $B$ after some time
• D. on the right side of $B$ when the strings are inclined at $15^\circ$ with $B$

Answer 1

Answer: (B)

Irrespective of amplitude,
both spheres take same time to reach the mean position, i.e., $\frac{T}{4} s$
$\therefore T=2 \pi \sqrt{\frac{l}{g}}=2 \times 3.14 \times \sqrt{\frac{1}{10}}=2\, s$
So, they will collide at $\frac{T}{4}=\frac{2}{4}=0.5\, s$