Here's a puzzle for you.

[Swanny]

Galileo pointed out that, ignoring air resistance, all bodies fall with the same acceleration. But what about objects sinking in water of different temperatures? Here is the puzzle: Suppose you drop a brick in each of two identical tanks. One of the tanks has water at 40 degrees F and the other has it at 30 degrees F. Which brick would sink faster?

:-?

[NiteW4tcher]

i have a headache ;D

[kn]

The one in the tank with 40 degree water.

[bobf279]

the colder water would be denser

[Scotty]

Duuuh! Water freezes at 32ºF (for the luddites who still use stone age units), so 30ºF is below freezing.... : : : A brick isn't going to sink very quickly through ice is it...?

The density of water remains pretty much the same between 1ºC and 99ºC, reducing a bit when it reaches solid phase (freezes), and substantially more when it reaches the gas phase (steam).

[@bj]

You haven't said anything about pressure - so - assuming a smidge above sea level...

30 F = -1 C

In other words ice. The brick will not sink - but sit on top the ice - assuming the water hasn't been super distilled - in which case - under certain circumstances - the water won't turn to ice...

40 F = 4 C

Assuming the above mentioned pressure caviats etc - water is liquid at this temperature - therefore the brick will sink.

Interesting to note however - that at 4C specifically - water reaches its highest density... higher than water at 3C or 5C

Or put another way - the brick will sink faster at 3C or 5C than at 4C

[Jon_W]

Assumng that the tanks are open to atnosphere at sea level and are pure water:

Scotty is right. The water in the lower tank would be frozen!


Here is a headache inducing one:

If you drop two identicle dimension spheres, with the same surface finish and dropped from the same height. One shhere is of a heavy material (say iron) the other of a light material (say wood).

Experement has shown that the wooden one will hit the ground first.

Why??

[b_m1957]

Here is a headache inducing one:

If you drop two identicle dimension spheres, with the same surface finish and dropped from the same height. One shhere is of a heavy material (say iron) the other of a light material (say wood).

Experement has shown that the wooden one will hit the ground first.

Why??

I'm struggling.

The full force formula applied to all 3 pairs of bodies gives a net acceleration of the Earth (in 1/r^2) biased towards the heavy ball. The force between the balls give a component to each of them in the direction of Earth (in 1/r^4), biased to the light ball.

Without more detailed analysis (and detail on the setup) seems to me the 1/r^2 would trump the 1/r^4 and the heavy ball would touch down first!

[Loops]

Assumng that the tanks are open to atnosphere at sea level and are pure water:

Scotty is right. The water in the lower tank would be frozen!


Here is a headache inducing one:

If you drop two identicle dimension spheres, with the same surface finish and dropped from the same height. One shhere is of a heavy material (say iron) the other of a light material (say wood).

Experement has shown that the wooden one will hit the ground first.

Why??

You attached the iron one to a bungee cord? :-/

[bobf279]

dropped at the same time?

oh and water at 30F is definitely denser as ice is frozen water