A particle is performing U.C.M. along the circumference of a circle of diameter 50 cm with frequency 2 Hz . The acceleration of the particle in $\mathrm{m} / \mathrm{s}^2$ is

Find the wrong statement from the following about the equation of stationary wave given by $Y=0.04 \cos (\pi x) \sin (50 \pi t) \mathrm{m}$ where $t$ is in second. Then for the stationary wave.

A convex lens of focal length ' $f$ ' is placed in contact with a concave lens of the same focal length. The equivalent focal length of the combination is

Two light balls are suspended as shown in figure. When a stream of air passes through the space between them, the distance between the balls will