Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
>
> First of all, there's no reason to believe the card measures energy "being
> transferred". The card measures temperature, which is something quite
> different.
Whoops, I forgot about the sacred heat cow on this list.
We tell students that GPE changed to KE during the fall, but I wish to
show that after the fall there is still evidence of energy. The energy
"goes" (verb of your choice) to another form. Temperature is _evidence_ of
the increase in thermal energy not the energy itself. Footprints are not feet
> Secondly, I suspect the measurement causes a pretty big perturbation in the
> collision phenomenon being measured. I'll bet the steel ball hitting a
> hard surface bounces markedly higher without the card than with the card.
Yes, but not much.
> In this situation, we have neither the ideal inelastic collision, nor the
> ideal elastic collision. That's fine; it's good to look at non-ideal
> situations. My concern is that the card measures only one of the
> nonidealities, while other small effects (and indeed big effects) go
> unmeasured.
>
I wish to show that the energy did not just disappear. This demo provides
_simple_ evidence that a change did occur and something is still moving
even if it cannot be seen or felt directly.
> If the objective is to demonstrate energy transfer, aren't there better
> ways to demonstrate that? (Carts on an air track come to mind.)
>
How do I get a tangible result? From a student's point of view, a pasco
cart loses speed after each bounce, but nothing is noticeably warmer.
> If the objective is to demonstrate energy dissipation, aren't there better
> ways to demonstrate that? (A nice steady rubbing motion comes to mind.)
OK, but I still need to convince HS students of where the GPE ends up.