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Solving Simple Harmonic Motion Problem with Energy

  • Thread starter Glorzifen
  • Start date
  • #1
25
0

Homework Statement


A 500g block on a spring is pulled 20cm and released. The motion has a period 0.8s.

What is the velocity when the block is 15.4cm from the equilibrium?


Homework Equations


Etotal = 0.5kx2 + 0.5mv2
w = [tex]\sqrt{k/m}[/tex]
w = 2pi*f
f = 1/T

The Attempt at a Solution



[FINDING K]
f = 1/0.8 = 1.25
w = 2pi*(1.25) = 7.85
7.85 = [tex]\sqrt{k/0.5}[/tex]
k = 30.8

[FINDING TOTAL ENERGY BY USING THE INITIAL VALUES]
Etotal = 0.5(30.8)(0.2)2
= 0.616

[USING THE TOTAL ENERGY WITH THE SECOND SET OF VALUES TO FIND V]
0.616 = 0.5(30.8)(0.154)2 + 0.5(0.5)(v)2
x = 1.7

Make sense to me...just hope its right. Any comments? Thanks as always - I appreciate the effort.
 

Answers and Replies

  • #2
ehild
Homework Helper
15,477
1,854


[USING THE TOTAL ENERGY WITH THE SECOND SET OF VALUES TO FIND V]
0.616 = 0.5(30.8)(0.154)2 + 0.5(0.5)(v)2
x = 1.7


It is all right, up to the last line. What is x? and what is 1.7? And how much is v?

ehild
 
  • #3
1,033
1
yeah its all good except you missed some calculations. My answer is around 1 I think.
 

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