An 18-lb block A slides in a vertical frictionless slot and is connected to a moving support B by means of a spring AB of constant k = 8 lb/ft. Knowing that the acceleration of the support is a = a_m sin ω_f t, where a_m = 5 ft/s² and ω_f = 6 rad/s, determine 

(a) The maximum displacement of block A, 

(b) The amplitude of the fluctuating force exerted by the spring on the block.

Transcribed Image Text:

B A Fig. P19.111 = am sin aft