Simple Harmonic Motion Question.

  • #1
Student3.41
71
0

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)[tex]\sqrt{m/k}[/tex]

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.
 

Answers and Replies

  • #2
cupid.callin
1,137
0
well do you know how to find force due to a spring?
 
  • #3
Student3.41
71
0
well do you know how to find force due to a spring?

Are you talking about hooke's law? F=-kx
 
  • #4
cupid.callin
1,137
0
yes!!!

Now, which force do you think is responsible for the decrease in height of mass (not -kx one)!!!
 
  • #5
Student3.41
71
0
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..
 
  • #6
cupid.callin
1,137
0
yes ... now as you will know that at point where net acc. on body will be zero ... Fnet = 0

can you figure out m/k now?
 
  • #7
Student3.41
71
0
yes ... now as you will know that at point where net acc. on body will be zero ... Fnet = 0

can you figure out m/k now?

Fnet=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
 
Last edited:

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