Posted by Ro on Friday, January 28, 2011 at 1:12pm.
A weight of 30.0 N is suspended from a spring that has a force constant of 180 N/m. The system is undamped and is subjected to a harmonic driving force of frequency 11.0 Hz, resulting in a forcedmotion amplitude of 5.00 cm. Determine the maximum value of the driving force.
PLEASE I NEED HELP

physics  drwls, Friday, January 28, 2011 at 1:40pm
Get the natural frequency of the system
wo = sqrt (k/m)
m = 30N/g = 3.06 kg
wo= 7.67 rad/s
The forced vibration frequency is
w = 2*pi*f = 17.28 rad/s
For oscillations of this type, without damping, the amplitude A is related to the force amplitude F by
A = F/[k(1  (w/wo)^2)]
= 0.245 F/m
You should do some reading on the subject of resonance to confirm the above formula.
Substitute 0.05m for A and solve for F