Q.
The displacement y of a particle, if given by y=4cos2(t/2)sin(1000t). This expression
may be considered to be a result of the superposition of how many simple harmonic motions?
∵ Equation of displacement of particle is y=4cos2(2t)sin(1000t)...(i)
or y=4[(21+cost)sin1000t] (∵cos2x=21+cos2x)
or y=3sin1000t+2costsin1000t
or y=2sin1000t+sin1001t+sint999t
[2sinAcosB=sin(A+B)+sin(A−B)]
Hence, Eq. (i) is the result of the superposition of three simple harmonic motion.