Greetings!
 Congratulations to all of you who were able to order
their free dinosaur skeleton kit last week.
We are really proud of you. 67% of all students who participated in
the quiz selected the correct answer.
Frank Cascarano, Physics Instructor at the Foothill College, CA
was so kind to explain the physics occurring inside the jar.
Here is the question again for those who don't remember: Maxi and
I had a little disagreement over the weight of flies in a
jar.
You place the jar on a scale. The scale will register
the most weight when the flies are
a) sitting on the bottom of the jar
b) flying around inside the jar
c) ... the weight of the jar is the same in both
cases
Click here to
watch Frank's explanation on our Youtube Channel or continue
reading his explanation.
"Short answer is: it weighs the
same whether the fly is hovering in the
middle of the jar or landed on
the floor of the jar. Basically, when you weigh the jar you are weighing the jar
and all of its contents. Another example, if the jar has air in
it, the jar will weigh more than a jar that has been evacuated and
just contains a vacuum.
Long answer is that it does
depend slightly on whether the fly is moving (well, actually, whether the fly is
accelerating). With the fly in the air the jar could weigh more or less
than with the fly standing on the floor of the jar, depending on whether
the fly begins moving up or down. Let's just say the average weight of
the jar+air+fly when the fly is flying is the same as the weight with
the fly on the floor of the jar."
We also liked deborah109's
answer a lot! Thanks for your excellent explanation!
"Since the jar is closed when it
is weighed all of its contents are being weighed. (jar, lid, air,
and flies no matter the positin of the flies.) The flies in motion
would still put pressure on the air then the jar then the
scale."
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