Re: Work-energy worries

[Jim Green <JMGreen@SISNA.COM>]

> But all of the PHYS-L debate about proper usage of work and energy
> terminology that I have followed has caused me to worry (possibly more than
> I should) about items like part b of this problem.  Would some object to
> this sort of question?  (The expected response is that the work should equal
> the total KE aquired by the boat, boater, and anchor.)

Well, your students are expected to know that W=dKE -- that work done on a
system = the increase in KE of the system.

But I agree that your wording would be better as "the work should equal the
increase in the level of KE by the boat etc."

The word "aquire" may imply to a student that the energy "flowed" into the
boat etc -- ie that KE is a substance -- terrible physics.

At least it is in my classroom.


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.