Oscillations of 1.5 kg Block on Spring: Frequency and Stretch

[Dooga Blackrazor]

1. A block of mass 1.5 kg is attached to the end of a vertical spring of force constant k=300 N/m. After the block comes to rest, it is pulled down a distance of 2.0 cm and released.
(a) What is the frequency of the resulting oscillations?
(b) What are the maximum and minimum amounts of stretch of the spring during the oscillations of the block?

(a) 2.3 Hz
(b) 2.9 cm and 6.9 cm


I used the formula T = 2(pie)(squaroot of m/k) with f = 1 /T and found the first answer; however, I'm now sure how to calculate the answers for the second part of the question. F = k*x (spring constant times displacement, but I'm not sure how that factors into the two answers.

Thanks in advance.

 

[Doc Al]

I'm now sure how to calculate the answers for the second part of the question. F = k*x (spring constant times displacement, but I'm not sure how that factors into the two answers.

They are measuring the stretch of the spring from its unstretched position (before the mass is attached). First find out where the equilibrium position is when the mass is attached. Then realize that the mass will oscillate about that point with the given amplitude.

 

[Dooga Blackrazor]

Thanks - I've got it now.