Posted by Amanda on Wednesday, July 14, 2010 at 10:28am.
Please show how you got the answers, not just the answers.
A 40.0 N force stretches a vertical spring 0.250 m.
(A) What mass must be suspended from the spring so that the system will oscillate with a period of 1.0 s?
(B) If the amplitude of the motion is 0.050 m and the period is as in part (a), where is the object and in what direction is it moving 0.35 s after it has passed the equilibrium position moving downwards?
(C) What force (magnitude and direction) does the spring exert on the object when it is 0.030 m below the equilibrium position, moving upward?

Physics  drwls, Wednesday, July 14, 2010 at 11:53am
From the force and deflecion information, the spring constant is k = F/X = 160 N/m
(A) Use the equation
P (period) = 2 pi sqrt(M/k)
(Solve for M)
(B) The total energy (kinetic + potential) = (1/2) k (Amplitude)^2
If t=0 is the equilibrium position,
X = A sin (2 pi t/P)
A = 0.050 m
Substitute t = 0.35 s
That is more than 1/4 period past the t=0 postion. It should be at negatime deflection but on the way back.
(C) X = 0.030 m. Multiply than by k for the force. The force wil be up.