NitPick:
If "the mass of the plastic cup is negligible", it won't sink! The mass
to volume ratio is the controlling factor.
(Does not affect your conclusion, though.)
Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net http://www.velocity.net/~trebor
----- Original Message -----
From: "Bob LaMontagne" <rlamont@POSTOFFICE.PROVIDENCE.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, June 04, 2003 10:45 AM
Subject: Re: Test question
| Herbert H Gottlieb wrote:
|
| > Brian Whatcott's response is good so far, but he failed
| > to consider the possibility that the weight of the second
| > added block would cause the cup to sink below the surface
| > of the water.
| >
| > Try again?
| >
|
| Assuming that the mass of the plastic cup is negligible, the water
| originally displaced is due to the weight of the 1st block. If a second
| block is added and the cup doesn't sink - we all agree that the water
level
| will rise by an amount determined by the weight of the 2nd block.
|
| If the cup sinks, the two blocks will now float to the surface - still
| displacing their weights - the weight of the 1st, pus the additional
weight
| of the 2nd - so again the water level rises. In fact it rises to the
same
| level that it would if the the cup didn't sink.
|
| bob at PC