A perosn normally weighting 50kg stands on a massless platform which oscillates up and down harmonically at a frequency of `2.0s^(-1)` and an amplitude 5.0 cm. A weighing machine on the platform gives the persons weight against time.
(a) Will there be any in weight of body , during the oscillation?
(b) If answer to part (a) is yes, what will be the maximum and minimum readin in the machine and at which position?

Explanation

(a) Yes, We know that when a platform on which a perosn of mass m is standing, is accelerating upwards with acceleration a, then the effective weight of the person becomes`=m(g+a)`.
If the platform is accelerating downwards with acceleration a, then effective weight of persono on platform `=m(g-a)` . During oscillation of a platform, a perosn standing on it, will be accelerated upwards and downwards with time. Due to it, the weight of a person on platform changes during the oscillation.
(b) Max. acceleration of platfor, `a_(max.)=omega^(2)r=4pi^(2)v^(2)r=4xx(3.14)^(2)xx2^(2)xx(5xx10^(-2))=7.89m//s^(2)` Maximum reading in machine while moving upwards `=m(g+a)=50(9.8+7.89)=884.5N`
Minimum readin in machine while moving downwards `=m(g-a)50(9.8-7.89)=95.5N`