Ch 9.3 Help

Question 2
KE= 1/2kx^2-mgx

straight off the lecture notes. the method posted above does not work

"Matthew Dawber" <matthew.dawber@stonybrook.edu>

hope that helps

The first formula for Question 2 worked for me. Just remember if you find the square root then in the KE formula you have to square the v again. You can also just leave it as is and do .5*m*v (not squared).

Alright, first list all the given quantities

PE = some# (check!)
k = some# (check!)

Now what is the question, what are you looking for? How far has the spring compressed? (In other words, the distance x )

x = ? <------- unknown, which also happens to be the answer

Think of an appropritate equation/formula that would satisfy the problem.

Well, PE = 1/2*k*x^2 pops into mind, don't you agree?

Okay, so now solve for the unknown, the x

So: PE = 1/2*k*x^2
Then: PE / (.5*k) = x^2
Therefore: sqrt [ PE / (.5*k) ] = x