More homework- need answers today or tomorrow! I think its something to do with boyancy or upthrust..... need more detail!
2007-09-01 05:03:37 · 15 answers · asked by Sez 3 in Science & Mathematics ➔ Physics
A boat is hollow, therefore it floats. A penny is a solid dense mass which isn't hollow, therefore it sinks because there is nothing to offset the water (i.e. the air)
A simple experiment: fill up the sink with water and get an empty plastic bottle. Put it on the water and it will sink. Take the bottle, squeeze it flat and put the lid back on. Then put it in the water and see what happens.
2007-09-01 05:11:16 · answer #1 · answered by Anonymous · 0⤊ 4⤋
f = W - B; where the net force f is the weight W minus bouyancy B. When f = 0 = ma; the body of mass m is not accelerating (a = 0).
The ship floats because after it sinks so far, its buoyancy B = W; so that, f = ma = W - B = 0. Bouyancy = rho V; where rho is the weight density of water (or the mass density times g) and V is the volume of water the boat displaces when it stops sinking. You should recognize that B is just the weight of the displaced water.
The coin sinks because f = ma = w - b > 0; that is, its buoyancy b never reaches its weight w; so b < w throughout. Another way to say this is that the weight of the water the coin displaces never equals the weight of the coin.
Thus, the coin sinks all the way into the water where it will continue to accelerate until such time that the drag force and buoyancy combine to offset the weight. In math talk that's f = ma = w - b - d = 0; where d is that drag force. d depends on several factors: water density, coefficient of drag for the coin, cross sectional area, and the velocity of the coin as it sinks through the water.
2007-09-01 05:37:02 · answer #2 · answered by oldprof 7 · 3⤊ 1⤋
Its actually all to do with displacement.
Say a ship weighs 1000 tons.
The ship will float, regardless of its material, when enough of the ship is underwater to displace 1000 tones or more of water.
This is possible because water is one of the heaviest materials known with 1 cubic metre = 1ton.
So the amount of ship below the water has to be more then 1000 cubic metres. This will weigh less then the water because it will be mostly hollow and will allow for a lot of weight above the water, ie the superstructure or where the bridge is and anything else you can see.
To demonstrate this look at an oil tanker. When its empty it will sit very high because less volume of ship is needed to displace the required weight of water.
When its full of thouds of tons of oil it sits much lower to compensate for the needed increase in water displacement.
So as long as an object diplaces more weight in water then the ship itself weighs it will float.
As long as the deck remains above the water line it will float.
2007-09-01 06:23:18 · answer #3 · answered by futuretopgun101 5 · 1⤊ 1⤋
The metal ship has a larger surface area and volume thus the density is lower than water. The ship is hollow unlike the coin which is solid. The volume of the water displaced is sufficient to keep the ship afloat. Yes, you are right and the principle involved is buoyancy.
2007-09-01 05:10:34 · answer #4 · answered by Swamy 7 · 0⤊ 1⤋
Actually, the reason is, the density of the ship is lower than the density of the coin. Since the volume occupied by the ship is thousands of times larger, compared to the coin, it able to stay afloat.
the equation density= mass/volume is important here. Also, its important to know that, the volume of the ship is displaced in a larger area of water, this disperses the weight of the object. The bouyant force exerted by the water will be albe to keep the dispersed weight of the boat afloat.
Good question, hope that helps!
2007-09-01 05:23:39 · answer #5 · answered by L 3 · 1⤊ 1⤋
The simple answer is water displacement.
A coin of the same weight as a ship would sink.
2007-09-01 05:08:34 · answer #6 · answered by Jack 4 · 1⤊ 1⤋
It has nothing to do with it. when a concave object is placed in a body of water, it occupies a greater volume because water cant access the air bubble in it, and if the average density of the ship (plus the air trapped in it) is smaller than 1 (water´s density) it will float.
2007-09-01 06:14:04 · answer #7 · answered by Anonymous · 1⤊ 1⤋
The shape has a a lot to do with it.Anything that can hold water will float on water,A coin cannot.
2007-09-01 05:10:34 · answer #8 · answered by taxed till i die,and then some. 7 · 0⤊ 1⤋
once in immerged a coin displaces water with its own volume.
Because the volumic mass of plain metal is greater than the one of water (in other words metal is heavier), the coin sink.
Because a boat moves a huge volume of water his lower volumic mass enable him to float (as overall its volumic mass is lower than the same volum of water.
2007-09-01 07:53:17 · answer #9 · answered by Anonymous · 0⤊ 1⤋
the surface area of the hull displaces the water in order to float
the penny sinks cuz its surface area is'nt enough
flatten it more with a hammer and give it a bow and it will float
2007-09-01 05:13:31 · answer #10 · answered by Gravy B 5 · 0⤊ 1⤋