Go Back   Physics Help Forum > College/University Physics Help > Advanced Mechanics

Advanced Mechanics Advanced Mechanics Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old May 2nd 2009, 07:26 PM   #1
Junior Member
 
Join Date: Apr 2009
Posts: 25
Spring Compression

Question:

A 1.00 kg object slides to the right on a surface having a coefficient of kinetic friction 0.250 (Fig. P7.54). The object has a speed of vi = 3.00 m/s when it makes contact with a light spring that has a force constant of 50.0 N/m. The object comes to rest after the spring has been compressed a distance d. The object is then forced toward the left by the spring and continues to move in that direction beyond the spring's unstretched position. The object finally comes to rest a distance D to the left of the unstretched spring.



Find the distance of compression d.

Alrighty, so I did the normal energy "recipe" of

1/2mv^2 - (mu)mg(x) = 1/2kd^2

However, no matter which way I try to solve it I run into the problem that I have two distance variable: x (from the initial position of the block to the block against the compressed spring) and d (the distance the spring is compressed). I'm not sure how to correlate these together and no inital distance is provided.

Any ideas?

Thanks a bunch!!
strgrl is offline   Reply With Quote
Old May 2nd 2009, 08:36 PM   #2
Physics Team
 
Join Date: Feb 2009
Location: India
Posts: 365
You need not worry about the initial position of the block. Start from the situation given in the second figure. The velocity 3.0 m/s is just before the object makes contact with the spring. So (1/2)mv^2 is the kinetic energy just before the contact. Now if the spring is compressed by a distance d then work done by friction will be (mu)mg(d) and not (mu)mg(x). Except this extra bit of salt your recipe is fine. So-

(1/2)mv^2 - (mu)mg(d) = (1/2)kd^2

For the final part you should have-

(1/2)kd^2 - (mu)mg(D+d) = (1/2)kD^2
Parvez is offline   Reply With Quote
Old May 3rd 2009, 01:36 PM   #3
Junior Member
 
Join Date: Apr 2009
Posts: 25
Thank you Parvez!
strgrl is offline   Reply With Quote
Reply

  Physics Help Forum > College/University Physics Help > Advanced Mechanics

Tags
compression, spring



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
spring compression sirvicxp Equilibrium and Elasticity 1 May 16th 2016 07:00 AM
Compression of a Spring pre pt marc Energy and Work 6 Sep 1st 2011 07:51 PM
Heat lost in isothermic compression arze Thermodynamics and Fluid Mechanics 1 Mar 3rd 2010 06:39 AM
Vapour-compression system Meesterslager Thermodynamics and Fluid Mechanics 0 Dec 19th 2009 09:01 AM
Compression of Submarine during dive Kiwi_Dave Advanced Mechanics 0 Dec 18th 2008 05:41 PM


Facebook Twitter Google+ RSS Feed