# A classical mechanics problem by Milun Moghe

**Classical Mechanics**Level 4

Any light radiation falling on the arc at any angle is absorbed completely. Out of all the light rays emitted from the source of power P=1watt the initial path of two rays are given.

At t=0 the source is switched ON. By some mechanism inside the part EOFG is an energy converter and oscillator which makes the lines oscillate with a very small amplitude with some instantaneous frequency (through an axis perpendicular to the given plane passing through O at time t=0) given by

\[f=k(P_{a})^{3}m^{4}d\]

Here K is constant \[P_{a}=Power(absorbed)\] ,d is the distance of the fixed source from the fixed imaginary axis (internal bisector of the lines of dotted lines)

The lines even though oscillate do not affect the circular shape of the arc only angle is reduced or increased

\[SM=5units\] , \[BO=b=100units\] M is a foot of pipendicular dropped on the axis from the source

\[AO=a=\frac{100}{3^{0.5}}units\] \[EO=GO=FO=50units\] \[tan\theta_{2}=\frac{1}{3^{0.5}}\] \[tan\theta_{1}=3^{0.5}\]

initially \[\alpha=\frac{\pi}{20}\]

Find the instantaneous frequency at t=7 seconds... the value of k=64

Neglect any other radiations and assume reflecting properties of light same as that when reflector is at rest , at all instants of time.