#$&*
PHY 201
Your 'cq_1_15.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** **
A rubber band begins exerting a tension force when its
length is 8 cm. As it is stretched to a length of 10
cm its tension increases with length, more or less
steadily, until at the 10 cm length the tension is 3
Newtons.
Between the 8 cm and 10 cm length, what are the
minimum and maximum tensions?
answer/question/discussion: ->->->->->->->->->->->-> :
0N and 3N
#$&*
Assuming that the tension in the rubber band is 100%
conservative (which is not actually the case) what is
its elastic potential energy at the 10 cm length?
answer/question/discussion: ->->->->->->->->->->->-> :
3N * .02m = .06 Joules
@& The work is based on the average, not the maximum, force.*@
#$&*
If all this potential energy is transferred to the
kinetic energy of an initially stationary 20 gram
domino, what will be the velocity of the domino?
answer/question/discussion: ->->->->->->->->->->->-> :
KE=1/2*m*v^2
+-sqrt((.06kg*m^2/s^2)/.02kg)=v,
.035m/s=v
#$&*
@& Good algebra but .06 / .02 is 3 and sqrt(3) is about 1.732.*@
If instead the rubber band is used to 'shoot' the
domino straight upward, then how high will it rise?
answer/question/discussion: ->->->->->->->->->->->-> :
vf^2=v0^2+(2*a*'ds),
(.035m/s)^2/(2*-9.8m/s^2)='ds,
This is wrong.
@& Given the correct velocity this would work.*@
#$&*
For University Physics students:
Why does it make sense to say that the PE change is
equal to the integral of the force vs. position
function over an appropriate interval, and what is the
appropriate interval?
answer/question/discussion: ->->->->->->->->->->->-> :
#$&*
** **
15 minutes
** **
@& Not bad. Revision is optional. No real need if you understand everything in the link below.*@
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#
#$&*