@LaLa – According to the Starbucks barista I got the info from 194F is the optimal trade-off between lack of taste (too cold) and too bitter (too hot).

]]>Just buy a thermometer, problem solved.

Yea you can do all the math as an exercise but a thermometer makes life simple and no need to play math games that as you admitted had an unknown factor (the tap water temp) so you can’t figure it out till you know the temp of the tap water. And how do you find out the temp of the tap water? you buy a thermometer, negating the need of the math in the first place as you just measure the temp of the water on the stove.

And oh yea the Good Will Store has thermometers all the time so it won’t cost much.

]]>I have been experimenting with maximizing coffee enjoyment per buck. My mr. coffee 4 cup is certainly a better deal than making a 12 cup pot, but I’m trying a french press mug too. I enjoy making a $20 / lb Kona coffee last longer than 3-4 bags of the $6 generic stuff that friends and family buy. Excellent coffee in moderation instead of tons of crap coffee.

]]>We also need some water temperature measuring here, for tofu production. Now to convince wife to get rid of our thermometer… ðŸ™‚ ]]>

OK, this is why I hated “story” problems in math as a kid. I can solve quadratic equations just fine, but I cannot figure out how to set up the equation for your hypothetical about the man and his wife. How ’bout a little help? ]]>

100X + 20*(1-X) = 90

==> X = 0.875 ]]>

@Andy R – I remove the heat source when it starts boiling. Hence, the driver of the phase change is gone. I should probably include the heat capacity of the glass container though, to some extent.

]]>Once the water reaches 100 Celsius, and heat continues to be applied, the water absorbs energy to transition through the phase change into steam.

Therefore, adding a small amount of cooler water to a larger amount of boiling water, may not actually decrease the temperature of the boiling water.

Try it sometime….of course you will have to borrow a thermometer.

]]>One of the driveway slabs had sunk down by two inches in front of the garage door. It was obvious by looking at it that the former owners had paid to have it mudjacked to no lasting effect.

Instead of paying to have it mudjacked again, I decided to try filling in the sunken section with “Quick Crete”-type concrete mix.

The math problem was to find the volume of the sunken area which needed to be filled in to level, & then given the total volume needed, figure out how many bags to buy.

Volume of the bags is 2/3 of a cubic foot.

Slab is sunken 2 inches on one side, but is level on the opposite side. Slab is 10 feet wide, & 7 feet from the sunken side to the level point. 2 inches = 1/6 of a foot.

Volume of a box = L * W * H = 7 * 10 * 1/6

That gives 11 & 2/3, which must be divided in 2 to get the volume of the wedge == 5 & 5/6

Divide that by the 2/3rds of a cubic foot per concrete bag & round up to the nearest whole number = 9 bags. Worked like a charm.

No more feeling like the car has to vault into the garage either, which I’m sure must be better for the suspension.

]]>Used to solve quadratic equations to find the length of the piles needed in a cantilever retaining wall.

]]>One of my exams involved finding TWO ways as possible of determining the height of a building using an altimeter; here are the two methods that scored me top marks:

METHOD 1: Tie a rope to the altimeter; lower the altimeter over the side of the building; keep lowering until it gently touches the ground; measure the length of the rope.

METHOD 2: Throw altimeter over side of building; time the fall; use that time to estimate the distance (you don’t expect me to google the formula for that, do you?)

]]>A man and woman have a combined age of 91

He is twice the age that she was when he was the age that she is now

It was fun to solve, but hardly real world

]]>@CestLaVie – I’m a lot more certain of the boiling point than I am of the faucet temperature. Using ice water to get a more precise fix is overkill. (As is correcting for pressure. I’m not living on a mountain.). As for the uncertainty induced by the faucet temperature, it’s small given the 12.5% (or so) that it contributes to the overall result.

]]>