Thank you for all of your answers
2007-04-03 12:23:00 · 11 answers · asked by furisded 3 in Science & Mathematics ➔ Physics
How dense does an object have to be to sink or float in water. something such as a wooden block with a desity of .7 would it sink or float in water?
2007-04-03 12:32:57 · update #1
If it's denser than the fluid it is in, it will sink. If it is less dense it will float. If you are talking about water, water weighs
1 gram / ml
= 1 gram / cubic cm
= 1kg / liter
= 1 metric ton / cubic m
If your object weighs less than that, it will float on water.
2007-04-03 12:27:31 · answer #1 · answered by Anonymous · 3⤊ 0⤋
Float in what?!
The critical condition is whether the object's overall density exceeds, equals, or is less than than the density of the fluid it is immersed in.
In pure water, under "standard conditions" of temperature and pressure, the density ' rho ' has to EXCEED 1 gm/cm^3 or 10^3 kg/m^3, to sink. At exactly those densities, things will be "neutrally buoyant" --- that means that in still water with no currents, they'll simply stay wherever they are put. "Floating," which generally means having a little of an object poking up above the horizontal surface level of the liquid, will occur when densities are LESS THAN those densities.
In sea water, or the Dead Sea, where dissolved salts increase the water's density, the critical numbers go up slightly.
On the other hand, the liquid mercury has 13.6 times the density of water. So, if an object's density is LESS THAN 13.6 km/cm^3 or 1.36 x 10^4 kg/m^3 (as is true for most common substances), it will FLOAT IN MERCURY! If YOU tried to dive into mercury (inadvisable on other toxic grounds), you would essentially slither along on its surface. (A dive with the kinetic energy that would take you down 13.6 feet in water, would only take you down a foot, i.e. just submerge your (horizontal!) body, in mercury.)
This fact that even heavy things can float on mercury has been made use of in telescope design. Certain telescopes on Mt. Wilson's in California floated in baths of mercury before its toxic nature was appreciated.
At the other extreme, of course, is floating (or rising) in air. A balloon with a gondola or other payload underneath it rises because the mean density of EVERYTHING it consists of (the obviously large balloon shape itself, the gondola or payload, the ballast it contains, even the much thinner ropes holding everything together) is less than that of the air that volume displaces. That is why the balloon needs to be filled with a large volume of substance significantly less dense than air --- traditionally hot air or helium, of course.
I hope that these answers have you floating on air!
Live long and prosper.
POSTSCRIPT Re. your "additional details" : Once you appreciate the general principle, it should be clear to you that an object with a density of 0.7 gm/cm^3 will DEFINITELY FLOAT IN WATER!
But PLEASE NOTE: Its density ISN'T just "0.7," it's "0.7 gm/cm^3" ! You MUST give its dimensions in the system of units in which you're measuring that density. Otherwise, just quoting a pure number gives it no physical context. Just look at what happens if you change from measuring density in gm/cm^3 to kg/m^3: the measure of it (the number associated with the particular choice of units) changes by a factor of 10^3 or 1,000 !
2007-04-03 12:27:09 · answer #2 · answered by Dr Spock 6 · 0⤊ 0⤋
If it is denser than water it sinks. If water is denser than the object, it floats. The density of water is 1 g/1cm3 at 4 degrees C.
2007-04-03 12:33:01 · answer #3 · answered by Ellie S 4 · 0⤊ 0⤋
How Dense Is Water
2016-11-04 05:29:51 · answer #4 · answered by branaugh 4 · 0⤊ 0⤋
The object has to be denser to sink. How depends on the material of the object, material the object floats/sinks, and gravity.
2007-04-03 12:29:19 · answer #5 · answered by Anonymous · 0⤊ 0⤋
To sink, the density has to be greater than whatever the fluid it's in's density. To float, it's just the opposite; lower density than the fluid's means floating.
2007-04-03 12:28:16 · answer #6 · answered by atmtarzy 2 · 0⤊ 0⤋
It will sink if it is denser than the liquid it is in.
It will float if it is less dense that the liquid it is in.
It will wander if it is the same density as the liquid it is in.
Eureka!
2007-04-03 12:27:53 · answer #7 · answered by Always Hopeful 6 · 0⤊ 0⤋
Denser than what its in, it sinks. Less dense than what its in, it floats.
2007-04-03 12:27:56 · answer #8 · answered by Hitchhiker 4 · 0⤊ 0⤋
more dense than water 1gram per cubic centimeter to sink
opposite to float?
2007-04-03 12:30:29 · answer #9 · answered by M Rod 1 · 0⤊ 0⤋
It will float on water.
2013-11-15 04:30:27 · answer #10 · answered by Bruce 1 · 0⤊ 0⤋