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Which of the following functions of time represent (a) simple harmonic. (b) periodic but not simple harmonic. and (c) non periodic motion ? Give period for each case of periodic motion (omega is any positive constant): 1)sin omega t - cos omega t2 ) sin^3 omega t3) 3 cos (pi//4 - 2omega t) 4)cos omegat+ cos 3 omega t + cos 5 omega t5)e^(-omega^2 t^2)6) 1+ omega t + omega^2 t^2 |
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Answer» Solution :`SIN omega t - cos omegat - sqrt2 [ sin omega t cos PI/4 - cos omega t sin (pi)/(4)] = sqrt2 sin (omega t- pi/4)` It is simple harmonic with a time period T =` (2pi)/(omega)` 2) `sin^3 omega t ` is a periodic function but not simple harmonic because `a ALPHA - y `condition is not satisfied. It is time period is `T= (2pi)/(omega)` 3) `3 cos (pi//4 - 2omega t) = 3 cos (2 omega t - pi//4) ` it is simple harmonic with a time period `T= (2pi)/(2omega) = pi/omega ` 4) `cos omega t + cos 3 omega t + cos 5 omega t ` is a periodic function but not simple harmonic . The time periods of each periodic function are `(2pi)/(omega) , (2pi)/(3omega) and (2pi)/(5omega)`. Since `(2pi)/(omega)` is the MULTIPLE of the other two periods, the given sum is periodic with the time period ` (2pi)/(omega` 5) `e^(-omega^2 t^2)` decreases and tends tozero as `t to oo` 6) `1 + omega t + omega^@ t^2 ` is not periodic as function with increase in t with out repetition. |
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