Calculating the distance the spring was compressed

[Line6spider]

A 1300 g mass is on a horizontal surface with μk = 0.380, and is in contact with a compressed massless spring with a spring constant of 600 N/m. When the spring is released, it does 8.61 J of work on the mass while returning to its equilibrium position. Calculate the distance the spring was compressed.

Also, what is the velocity of the mass just as it loses contact with the spring?



Any help would be appreciated, I'm pretty lost with this one.

 

[Ackbach]

Follow your http://www.mathhelpboards.com/f22/problem-solving-strategy-28/. What are your target variables? What are the physical principles involved, do you think?

 

[SammyS]

A 1300 g mass is on a horizontal surface with μk = 0.380, and is in contact with a compressed massless spring with a spring constant of 600 N/m. When the spring is released, it does 8.61 J of work on the mass while returning to its equilibrium position. Calculate the distance the spring was compressed.

Also, what is the velocity of the mass just as it loses contact with the spring?

Any help would be appreciated, I'm pretty lost with this one.

Hello Line6spider. Welcome to PF !

What have you tried?

Where are you stuck?

The following is an excerpt from the rules of this Forum in regard to Homework Help.

Homework Help Guidelines

Any and all high school and undergraduate homework assignments or textbook style exercises for which you are seeking assistance are to be posted in the appropriate forum in our Homework & Coursework Questions area--not in blogs, visitor messages, PMs, or the main technical forums. This should be done whether the problem is part of one's assigned coursework or just independent study. The reason for this is that the scientific and mathematical sections of Physics Forums are to be reserved for discussions and not academic assistance. Since graduate level assignments are meant to be more thought provoking (and hence more worthy of discussion), graduate level questions will be allowed in the relevant part of the main section of PF, provided that the graduate student attempts the problem and shows his work.

NOTE: You MUST show that you have attempted to answer your question in order to receive help. You MUST make use of the homework template, which automatically appears when a new topic is created in the homework help forums. Once your question or problem has been responded to, do not go back and delete (or edit) your original post.

We do not support cheating in any form: Do not ask for solution manuals, answers to exams, or instructor's manuals. Every school and instructor has their own policies or honor codes on what constitutes cheating, and it is up to the individual student to adhere to those policies when seeking help here. If you are in doubt as to whether you are permitted to seek help, consider erring on the side of caution and not asking for help.

On helping with questions: Any and all assistance given to homework assignments or textbook style exercises should be given only after the questioner has shown some effort in solving the problem. If no attempt is made then the questioner should be asked to provide one before any assistance is given. Under no circumstances should complete solutions be provided to a questioner, whether or not an attempt has been made.​

 

[rude man]

1. all the spring energy was imparted to the mass in one way or another, so how far was the spring compressed?
2. before spring release, all the energy was stored in the spring. After release, part of the energy went into friction loss and part remained in the form of kinetic energy. What was the friction energy loss?

To answer the latter questinn - at what point is contact lost between the spring and the mass?

 

[Line6spider]

Hello Line6spider. Welcome to PF !

What have you tried?

Where are you stuck?

Well someone told me I could use 1/2k x^2= PE but it didn't really work out.

Also, I tried using F=ma and Work is Force times Distance. So F=ma=W/d, but I am not sure where to go from there.

 

[SammyS]

Well someone told me I could use 1/2k x^2= PE but it didn't really work out.

Also, I tried using F=ma and Work is Force times Distance. So F=ma=W/d, but I'm not sure where to go from there.

For a spring it is true that PE = (1/2)kx² . --- well, of course that is if x is the length by which the spring is compressed (or stretched).

Let's see how you actually went about trying to use that, so we can tell where you're going wrong.

 

[Line6spider]

Would the PE equal the work in this case?

I tried (1/2)kx2=8.61J

Then I could say X=√((2*8.61)/600) right?

 

[rude man]

Would the PE equal the work in this case?

I tried (1/2)kx2=8.61J

Then I could say X=√((2*8.61)/600) right?

Excellent start!
Now, what happened to that energy?

 

[SammyS]

Would the PE equal the work in this case?

I tried (1/2)kx2=8.61J

Then I could say X=√((2*8.61)/600) right?

The PE is equal to the work done by the spring. There is another important force here which also does work.