Solve Your Spring Problems Now - Expert Help Available

[dsptl]

http://img222.imageshack.us/img222/8623/69793936pc8.jpg
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Please Help some1??

To be honest I don't what to do...

 

[Hootenanny]

Saying that you have no idea doesn't count as an attempted solution. Have you read your class notes and/or text?

 

[dsptl]

my professor doesn't go in details and book is to consusing but still I will give a try:

attempt: First I thought to use

W = delta KE + delta PE

but I was confused b/c i did not see a way to put those spring forces in there

so i was kindly asking for a help

 

[Hootenanny]

my professor doesn't go in details and book is to consusing but still I will give a try:

attempt: First I thought to use

W = delta KE + delta PE

but I was confused b/c i did not see a way to put those spring forces in there

so i was kindly asking for a help

Thank you for trying, your threads will generally get answered a lot quick if you show an attempted solution.

You're right to approach the problem using conservation of energy. You know that the work done by friction and the 400 N/m spring must be equal to the energy stored in the N/m spring.

Can you go from here?

 

[dsptl]

is it like this:

F x S = Ef - Ei

 

[Hootenanny]

is it like this:

F x S = Ef - Ei

We'll take it a step at a time. What is the energy stored in the 200N/m spring before the block is released?

 

[dsptl]

= .5k(x.x) + .5mv.v + mgh

 

[Hootenanny]

= .5k(x.x) + .5mv.v + mgh

Could you explain how each of the terms arise, what does each term represent?

 

[dsptl]

1st is spring force , 2nd is kinetic energy and 3rd is potential enery, which is 0.

 

[Hootenanny]

1st is spring force , 2nd is kinetic energy and 3rd is potential enery, which is 0.

Good. What about the kinetic energy, is that non-zero before the block is released?

 

[dsptl]

i think it is zero since Vi is 0

 

[Hootenanny]

i think it is zero since Vi is 0

Correct. So, the total energy of the system is simply the energy stored by the spring, can you calculate it?

Now, when the block reaches the 400N/m spring is compresses it. So how much energy is stored in this spring? Can you also calculate this value?

 

[dsptl]

at intial = .5(200N/m)(.1 x .1) = 1N

at Final = .5(4000N/m)(.05 x .05) = .5 N

 

[dsptl]

do i just add them together?

 

[Hootenanny]

do i just add them together?

No.

You started off with this much energy:

at intial = .5(200N/m)(.1 x .1) = 1N

And ended up with this much energy:

at Final = .5(4000N/m)(.05 x .05) = .5 N

Where did the rest of the energy go?

You also need to be careful with your units, the Newton is not a measure of energy.