GR8677 #34


Problem



Mechanics}Potential Energy
Recall the lovely relation,


Alternate Solutions 
TimToolMan 20180403 00:15:02  Simple Unit argument.\\\\r\\\\nEnergy is in units of \\\\r\\\\nSo we can get the units of k to be \\\\r\\\\nForce must be in units of \\\\r\\\\nKeeping k\\\\\\\'s units in mind, there are only 2 solutions with these units of force: B & E\\\\r\\\\nNo gravity in this question, so it must be B  

Comments 
TimToolMan 20180403 00:15:02  Simple Unit argument.\\\\r\\\\nEnergy is in units of \\\\r\\\\nSo we can get the units of k to be \\\\r\\\\nForce must be in units of \\\\r\\\\nKeeping k\\\\\\\'s units in mind, there are only 2 solutions with these units of force: B & E\\\\r\\\\nNo gravity in this question, so it must be B   OrrinJelo 20090804 10:37:53  The easiest way is by doing dimensional analysis. (A) is in units of energy, same with (C). (D) is energy times distance. This leaves (B) and (E). (E) is the force associated with gravity, which our potential energy equation looks nothing like the gravitational potential equation. We are left with (B).
neon37 20101101 10:42:12 
I think thats the hardest way to do this. Easiest is the solution given. You should remember that . If you dont then you should think about memorizing that one. It will be mighty helpful.

pam d 20110924 09:53:55 
neon37, I second that.

mpdude8 20120415 21:03:04 
Even though that's the long route for this problem, knowing the units of "k" will be useful in 35 and 36.

  jitin1984 20061027 15:15:32  hey
i cant get enough practice problems for quant. i have got schaum seeries but it has only derivations any one has any material plz i want it   Mexicorn 20051108 12:10:14  I think you mean instead of for the potential given.
yosun 20051109 02:27:05 
Mexicorn: thanks for the typoalert; it has been corrected.

 

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