Question

A block hangs in equilibrium from a vertical spring. When a second identical block is added, the original block sags by 5.00 cm. What is the oscillation frequency of the two block system?

Answer 1

F=kx = mg

x=mg/k
but for the second block we have

x+.05=2mg/k

setting the x equal..

mg/k-2mg/k=-.05
-mg/k=-.05
k= mg/.05

now frequency:

f= 1/2pi sqrt (k/m)

put that k int the expression, and you have the answer.