If helium is lighter than air and air is heavier, why doesn't theair push it down?
It does push it down. But you seem to be confused between the properties of solids and fluids. A solid consists of atoms or molecules connected together in a lattice of some form, making it - well - solid. If I put a gold slab on top of an aluminium slab, the gold slab will push the other down, but the aluminium slab will stay down because it's got no option - it can't 'flow', it can't escape! Fluids (liquids and gases), on the other hand, are not restricted by interconnecting forces forming a solid lattice, so when a force or pressure acts upon them, they will move or flow accordingly. So the lighter fluid will tend to move above the heavier one because gravity is exerting more pull on the heavier fluid (by definition - that's basically what 'heavier' means). Look at it this way: if you placed a rock onto a pond of water that had frozen over due to cold weather, the rock wouldn't move down, would it? It would stay sitting on top of the ice. But if the weather warms up and the ice melts, the rock would fall down through the liquid (water) to the bottom of the pond. The less dense fluid will automatically flow above anything denser than it. Laws of gravity.
Is helium an anti-gravity device? I know its lighter than air and rises, but what would happen in space?
Helium does not defy gravity. It is simply less dense than air, therefore air exerts a buoyant force against it. This force is stronger than the Earth's gravitational pull, so helium rises. At higher altitudes, air becomes less dense and the buoyant force acting on the helium will be smaller. It will stop rising when the buoyant force pushing it up is equal to the gravitational force pulling it down. A helium balloon in space would expand, and may even burst, because there would be nothing pressing against the outside of it to counteract the pressure of the helium pushing against the inside of it. The only thing holding it together would be the tension in the rubber.
Is helium an anti-gravity device? I know its lighter than air and rises, but what would happen in space?
Helium does not defy gravity. It is simply less dense than air, therefore air exerts a buoyant force against it. This force is stronger than the Earth's gravitational pull, so helium rises. At higher altitudes, air becomes less dense and the buoyant force acting on the helium will be smaller. It will stop rising when the buoyant force pushing it up is equal to the gravitational force pulling it down. A helium balloon in space would expand, and may even burst, because there would be nothing pressing against the outside of it to counteract the pressure of the helium pushing against the inside of it. The only thing holding it together would be the tension in the rubber.
Why doesn`t gravity affect hellium ?
While helium itself doesn't actually defy gravity, it is lighter than air and floats upward as descending air pushes it out of the way. Like a bubble in water, the helium goes up to make room for the air going down. The buoyant force that acts on the helium is equal to the weight of air that the helium displaces. A cubic foot of air weighs about 0.078 pounds so the upward buoyant force on a cubic foot of helium is about 0.078 pounds. A cubic foot of helium weighs only about 0.011 pounds. The difference between the upward buoyant force on the cubic foot of helium and the weight of the helium is the amount of extra weight that the helium can lift; about 0.067 pounds. Since you weigh 85 pounds, it would take about 1300 cubic feet of helium to lift you and a thin balloon up into the air. That's a balloon about 13.5 feet in diameter.
Why is helium lighter than air?
Matter is made of particles. If the particles are fixed in place by strong attractions, that's a solid. If the particles are not fixed in place, but still held together by attractions, so that the particles can move around, that's a liquid. If there are no attractions holding the particles to each other, that's a gas. It is not uncommon for people to think of gas as not having weight because they move through the air with no perceived resistance. But recall that matter is anything that has mass and takes up space. You can blow up a balloon, so the air takes up space, and therefore it must have mass. The amount of air in a 2L soda bottle has a mass of about 2.6g. The amount of air in a 12' x 12' x 8' bedroom (~1150 cubic feet = 32,600L) weighs about 84,000g or about 186 pounds. Helium is lighter than air because its particles have just 2 protons and 2 neutrons. A 2L bottle of He will have a mass of just 0.36g. Air is mostly nitrogen molecules, N2. One atom of nitrogen has 7 protons and 7 neutrons, so N2 would have 14 protons and 14 neutrons for a total of 28 nucleons, or 7 times heavier than He. (This information can be deduced from the information on a periodic table. As you know, ice floats on water. Water has a density of about 1.0g/mL Ice has a density of about 0.93g/mL Less dense materials float on more dense materials. Since He is less dense ("lighter") than air, He balloon rise. Since CO2 is more dense than air, it would sink.
Why do things lighter than air defy gravity ?
They don't defy gravity. It's the buoyant forces on the object that pushes it upwards. The buoyant force is the weight of the fluid displaced by the object. Take a balloon for example. If you dunk it underwater, It will float. Sure the balloon is light and all, but since it takes up such a large volume, the weight of water it displaces is pretty significant, so the buoyant force (acting upwards) overcomes the weight (pulling down). The same thing happens for helium balloons. It's all about the atmosphere. If you were to take a balloon to the moon where this no atmosphere, it would sink. There would be no upward buoyant force acting on it.
Does gravity have an effect on air particles?
Dear Friend read completely and get your point cleared with my answer Gravity is different from the other known forces of nature. All bodies, big and small, accelerate at equal rates in any given gravitational field. That property is opposite to our everyday experience, in which more massive bodies require more work to move or accelerate than less massive ones. That gravity accelerates masses of all size with equal ease is so anti-intuitive that people universally believed otherwise until Galileo’s demonstration at the Leaning Tower of Pisa. He simultaneously dropped a heavy and a light mass (both heavy enough that air resistance was not a factor), and observers below tried to time which hit first and by how much. But to the astonishment of the observers, who were certain that the heavier body would fall faster, the two masses reached the ground at the same time. When an object is falling it has a constant acceleration....which basically means it is constantly speeding up When objects fall towards the earth, gravity pulls it down at an acceleration of 9.8 meters per second squared so every second the object falls....its velocity increases by 9.8 meters per second. Air resistance does the opposite of gravity. Unlike gravity, which increases an object's velocity, air resistance slows the the object down, hence the word resistance. Its a hard concept, but luckily my physics class just tested on it. I hope it this helps you. If it doesn't, go on cramster.com and search for your physics book. If you make a free username and password, you gain access to all of the questions, solutions, and explanations for your book. ne of the forces acting on a parcel of air is gravity.It pulls the air downwards and produces a density distribution in such a way that heavier air is below the lighter air.In a high pressure area,cold and heavy air sinks from a higher level and continues its journey as a horizontal wind(which we usually refer to as wind) towards a low pressure area where it rises and completes the wind circulation (like Hadley cell).So,gravity affects the wind also to some extent.
If helium is heated, does it get lighter?
Helium only becomes "lighter" when it is less dense, presuming that's the kind of "light" you are referring to. If you heat helium in a ballon that can expand, but you don't heat the surrounding air by the same amount (equalizing the pressure difference), then indeed helium will become "lighter" in the sense that it will be less dense. This is because increasing the temperature will increase its pressure until the volume expands to match closer to the pressure with the outside, while accounting for the expandability of the balloon. If you heat helium in a rigid container, or if you heat a contained volume of air, some of which is helium contained within a balloon that is within the larger volume, then no, the density of helium will not change. Actually, depending on the characteristics of the balloon finality could actually decrease, as the pressure of the heavier outside air increases as its temperature goes up (this depends on the exact flexibility/rigidity characteristics of the balloon's material). Now, in the pure sense of mass (or weight measured otherwise within a vaccum), a given number of helium atoms will have the same mass or weight, irrespective of its temperature.For example, if you put a quantity of helium in a balloon, put that balloon in a vacuum chamber, and, within that vacuum chamber, you placed the balloon on a weight or mass scale, then the weight or mass of the ballon would remain unchanged by heating it. If the balloon popped, you wouldn't be able to measure its weight or mass anymore, but that's a different problem.
Does gravity affect gas?
Dear Friend read completely and get your point cleared with my answerGravity is different from the other known forces of nature. All bodies, big and small, accelerate at equal rates in any given gravitational field. That property is opposite to our everyday experience, in which more massive bodies require more work to move or accelerate than less massive ones. That gravity accelerates masses of all size with equal ease is so anti-intuitive that people universally believed otherwise until Galileo’s demonstration at the Leaning Tower of Pisa. He simultaneously dropped a heavy and a light mass (both heavy enough that air resistance was not a factor), and observers below tried to time which hit first and by how much. But to the astonishment of the observers, who were certain that the heavier body would fall faster, the two masses reached the ground at the same time.When an object is falling it has a constant acceleration....which basically means it is constantly speeding upWhen objects fall towards the earth, gravity pulls it down at an acceleration of 9.8 meters per second squaredso every second the object falls....its velocity increases by 9.8 meters per second.Air resistance does the opposite of gravity. Unlike gravity, which increases an object's velocity, air resistance slows the the object down, hence the word resistance.Its a hard concept, but luckily my physics class just tested on it. It pulls the air downwards and produces a density distribution in such a way that heavier air is below the lighter air.In a high pressure area,cold and heavy air sinks from a higher level and continues its journey as a horizontal wind(which we usually refer to as wind) towards a low pressure area where it rises and completes the wind circulation (like Hadley cell).So,gravity affects the wind also to some extent.