will it take off?

[daTeacha]

You're right on the aqueduct, Pat. The problem says "comes along". When the guy jumps ship, he exerts a force on the boat, but the boat is going to temporarily displace more water during the time of his departure. If the aqueduct is working ideally, the displaced water will be instantaneously moved from the vicinity, but realistically, the act of jumping will transmit some degree of hydrostatic shock through the system to walls and floor of the aqueduct, possibly causing a catastrophic failure and drowning all the residents of the village below as the thing empties itself.

I have a tendency to skim through these things since I'm basically stealing minutes at school for a lot of them. I'm at lunch right now, prep time actually. I look at this diversion as mentally preparing me to deal with a couple crews of incredibly untalented freshmen. I spent about 20 minutes day before yesterday trying to get them to see that the change in temperature could be expressed as |T1 - T2| rather than as a known quantity. At home my internet connection is faster than dial-up, but it has a tendency to break down at random intervals, so prolonged internet time is not really available.

 

[SPYDERLK]

Quote What about a glass of ice water filled to brim and a little more (aided by surface tension) such that a single drop more and it will spill over. The ice cubes are floating well above the rim of the glass. How much water will spill over when the ice melts and adds its water to the glass?

- -The amt of water that will spill is the amount equal in weight to the air displaced by the ice cube volume that is above the water surface.- -
Larry

 

[SPYDERLK]

Simple one for some, not for others.

You are at a county fair. There is a vendor of homemade ice cream running his ice cream machines with a hit and miss engine. You stop to watch the engine run and begin conversing with the vendor. He offers you a free ice cream if you can tell him what the temperature of the ice cream is and how you know the answer. Since you really want some ice cream and have no money, what do you say? You do not have a thermometer available.

Id say I would have to taste it to tell. Then Id say it was freezing because if it wasnt it would have been running, but that now it is 98.6. - -Its impossible to know its original temperature.
Larry

 

[patrick_g]

Larry, Very good! This may in fact be less than the ONE DROP (depending on your drop size) with no run over but your theory is on target AND drop size was not stated.

Now then daTeacha, before we become aquaduct half empty pessimists, mentally inundating and drowning the innocents below in mid orgy we need to allow for the entire spectrum of jump magnitudes. I suggest there is a gentle jump possible that would not be the straw that broke the aquaducts back. Until getting into jumps so small as to envoke quantitization of quantum mech there is essentially a continuum of jump magnitudes and similar to Zeno's paradox however arbitrarily close to failing you construe the aquaduct to be the jumper should be able to jump at a magnitude of shock just below destruction threshold.

Pat

 

[SPYDERLK]

Quote Adding the cream immediately lowers the delta T between the coffee and the ambient temp. The delta T is the big driver in heat transfer in this situation. Once the cream is added there is an immediate reduction of temp and the exponential rate of the coffee's approach to the asymptote (room temp) continues but the area under the curve (heat loss) is minimized. None of the other strategies are as effective. The main driver is delta T and the non-linear heat loss. Reducing the delta up front is THE TICKET.

I agree. this is the major part of any solution of these parameters. A major one that has been neglected is evaporation. Adding the cream will benefit this as well. In order to optimize tho, I would do the following:
1) Add MOST of the cream and stir with a straw or plastic spoon,
2) Allow solution to quiet,
3) Add the small remainder of cream,
4) Drape a paper napkin over the cup,
5) Keep the cup still.

Larry

 

[patrick_g]

Larry, You may note that I mentioned TWO uses for napkins! 1. cover with napkin
2. start a fire with napkins.

Patrick

 

[daTeacha]

If indeed the ship jumper actually jumps rather than gingerly steps off the boat as it parallels the side of the aqueduct, he will impart an acceleration to the boat and thence to the water. Perhaps he could grab an overhead beam of some sort and lift himself from the boat also, but any jumping action on his part could overload the aqueduct.

About the billiard balls -- it will not work if you put 6 on each side to start.

 

[daTeacha]

Larry, You may note that I mentioned TWO uses for napkins! 1. cover with napkin
2. start a fire with napkins.

Patrick

I believe starting a fire from napkins might be considered causing an undue disturbance for the waitress, management, and other patrons of the restaurant. Since you are wanting to keep your coffee warm without causing any problems at all, this approach would have to be discounted. Why not say you move to a window and you use your glasses to focus solar energy into the cup. This only works if you're farsighted, though.

 

[patrick_g]

daTeacha, Again you assume too much. You assume JUMP WITH SUFFICIENT FORCE SO AS TO CAUSE THE AQUADUCT TO FAIL when the problem said jump. As previously stated there is a continuum of jump magnitudes. Any arbitrarily weak aquaduct could be jumped into with an arbitrarily smaller jump than the destructive threshold.

Familiar with the argument of the beard? Good, well it doesn't apply hear.. na na na naaaaa nah!

Pat

 

[patrick_g]

I believe starting a fire from napkins might be considered causing an undue disturbance for the waitress, management, and other patrons of the restaurant. Since you are wanting to keep your coffee warm without causing any problems at all, this approach would have to be discounted. Why not say you move to a window and you use your glasses to focus solar energy into the cup. This only works if you're farsighted, though.

Again you assume too much or stated another way over limit the possibilities (truly stiffling.)

You assume the skill in building a fire is so poor as to emit lots of attention drawing smoke or that the fire builder wouldn't shield a direct view of the flames with a couple menus is to lack imagination. To stay "in character" as you alluded, one would have to be stealthy with the fire.

Pat