Posted by Anand on .
A 1.70 kg object attached to a spring moves without friction and is driven by an external force given by F = (3.00 N) sin(2πt).
(a) If the force constant of the spring is 20.0 N/m, determine the period.
_____s For this one I tried 2*pi*sqrt(1.7/20) but it said my answer differed from the correct answer by more than 10%.
(b) If the force constant of the spring is 20.0 N/m, determine the amplitude of the motion.
_____cm For this one I tried kx = 3 sin(2πt) > x = (3/k) sin 2πt > Amplitude = 3/k = 3/20 = 0.15 m = 15 cm but it said I was off by 100%.
Any help would be appreciated!

College Physics 
Elena,
Frequency will be the driving frequency
ω = 2π (s^1),
T = 2•π/ ω = 1 s.
Amplitude
A = (F/m)/(ω^2  ω(o)^2)=
=(F/m)/(ω^2  k/m)=
= (3/1.7)/(4•π ^2  20/1.7) = 0.064 m.