Homework Help Forum: Physics

Posted by Rachel on Friday, November 6, 2009 at 10:19am.

If a 40 kg brick and a 400 kg brick each dropped from 1 m above a trampoline, find the lowest position of each brick. Assume the trampoline is a simple spring obeying Hooke's law with a k value of 12 000 N/m. I know i must use Fs= kx, but where do I start? Do i find Fg at 1 m?

• Physics - bobpursley, Friday, November 6, 2009 at 10:26am

  I would do it with energy. mg(h+x)=1/2 k x^2 then solve for x in each case.

  
  

• Physics - Rachel, Friday, November 6, 2009 at 10:29am

  okay, but what is the start of that eq'n? It looks similar to Eg=Ek ?

  
  

• Physics - bobpursley, Friday, November 6, 2009 at 10:31am

  PEintrampoline=PE gravity lost

  
  

• Physics - Rachel, Friday, November 6, 2009 at 10:37am

  pe= potential energy?

  
  

• Physics - Rachel, Friday, November 6, 2009 at 10:38am

  and how do i solve for x when it is on oth sides of the eq'n?

  
  

• Physics - bobpursley, Friday, November 6, 2009 at 10:39am

  multiply it all out, you will get a quadratic equation. Use the quadratic formula.

  
  

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