Simple Harmonic Motion Question.

[Student3.41]

Homework Statement

When a mass is hung from a spring, the spring elongates by 10.6cm. What will the period of the resulting oscillations be if the mass is displaced from equilibrium?

Homework Equations

T=2(pi)\sqrt{m/k}

The Attempt at a Solution

I have no clue what do with this question, if I am not given a mass or spring constant. I tried using Newtons 2nd Law to find k but without knowing the mass I ended up with two unknowns.

 

[cupid.callin]

well do you know how to find force due to a spring?

 

[Student3.41]

well do you know how to find force due to a spring?

Are you talking about hooke's law? F=-kx

 

[cupid.callin]

yes!

Now, which force do you think is responsible for the decrease in height of mass (not -kx one)!

 

[Student3.41]

yes!

Now, which force do you think is responsible for the decrease in height of mass (not -kx one)!

Well the only other force acting on the object is gravity..

 

[cupid.callin]

yes ... now as you will know that at point where net acc. on body will be zero ... F_net = 0

can you figure out m/k now?

 

[Student3.41]

yes ... now as you will know that at point where net acc. on body will be zero ... F_net = 0

can you figure out m/k now?

F_net=0
Fs-mg=0
kx=mg
x/g=m/k

(0.106/9.81)=m/k

=0.104= m/k

T=2(pi)square(0.104)root
Got the answer!

Thanks! I was approaching the problem right, I just never noticed m/k=x/g... appreciate the help