Ascending Balloon

The atmospheric pressure decreases while the balloon rises, but the pressure inside the balloon remains the same all the time. It means that the atmospheric pressure becomes weaker than the internal pressure of the balloon and the ballon will expand.

Imagine a balloon in the bottom of an ocean (which is more or less what is happening here, because air is a fluid). The pressure on the outside will squeeze the balloon. As the balloon rises, the water will squeeze on the balloon less so that the helium molecules can expand the balloon more. Therefore, the balloon increases in volume.

1. Equilibrium/ Boyle's law : The balloon's internal pressure must equal the ambient atmospheric pressure. Since helium is less dense than air, the balloon volume increases. (Further assumption: the balloon is made of an elastic/stretchy material.)
2. Archimedes' Principle : This expansion will cause the balloon to rise.
3. Atmospheric pressure: As the balloon rises, ambient atmospheric pressure decreases.
4. From premise #1, the ambient pressure continues to decrease, and so the balloon will continue to expand ...

According to the ideal gas law, $PV = nRT$ where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature. Given that the problem states that no heat enters or leaves the balloon and gases cannot enter or leave the balloon , n and T are constants. Thus the entire expression $nRT$ is constant, which means that at higher altitudes where atmospheric pressure is decreased, volume must increase. This was my first time publishing an answer, so I hope that this helped and I am not incorrect.

The pressure of the gas in the balloon decreases. This causes the balloon to expand. The thermal expansion means that the temperature drops (even though no heat escapes!); this temperature drop reduces the expansion of the balloon, but does not prevent it completely.

This is an example of adiabatic expansion .

As the ballon rises above ground level, the atmospheric pressure continuously reduces. As the external pressure on the balloon reduces, it expands and it's volume increases.

The air pressure on surface of earth is greater and this pressure restricts the balloon's helium gas from expansion. As we move up in sky the air pressure decreases, so for balloon pressure keeps on decreasing thus helium starts expanding.

the balloon is goes up by the increasement helium

also not mentioned in any of the answers is gravity force . this force pushes down on the balloon, more specifically the center of mass of the balloon. as the balloon rises this force decreases since as we know the gravitational force between two objects ( in this case the earth & balloon) weakens the farther the objects are apart . thus with less gravitational force , the elastic balloon will expand out ward as it rises along with as other answers correctly point out , atmospheric pressure decreasing.

The interior pressure remains the same but the pressure outside the balloon drops as it rises. With less and less exterior pressure the balloon expands till it pops.

eventually does the temperature drop to balance out, reduce effect, or reverse effect of lower atmospheric pressure?

Gases usually have more volume as the inter molecular space between the molecules are more hence they see to occupy more volume.In the above problem helium which is lighter is definitely having more inter molecular spacing than air,hence will more volume.

At equilibrium, the gaseous pressure in the balloon equals to that of the atmosphere. As the balloon rises, the surrounding atmospheric pressure drops, so the gaseous pressure in the balloon also drops accordingly to equalize. Assuming there is no heat transfer between the helium in the balloon and air, there is no temperature change in the balloon. Since potential energy is conserved, the balloon expands according roughly to $PV = \ constant$ of an ideal gas. Therefore, its volume increases.

Remember that $\text{pressure} = \frac{\text{force}}{\text{area}}$ .

At first, the internal pressure of the helium and the external pressure of the atmosphere will be equal. Atmospheric pressure is lower at higher altitudes, so the balloon must adjust accordingly. Although the balloon cannot change the atmospheric pressure, it can change the helium pressure by increasing area. When it does this, the denominator of the fraction becomes larger, so the pressure of the helium will decrease. The balloon must expand to make this change, so the volume will $\boxed{\text{increase}}$ .

As height increases pressure decreases due to which the inside of ballon will have a high air pressure and outside will have low air pressure. The property of fluids(gases and liquids) is that they will flow to low pressure from high pressure. Due to this the gas from high pressure will try to move from high pressure but since it is trapped in baloon it will exert force on ballon trying to expand and will eventually burst the ballon.

as we height increases the atmospheric pressure decreases, and as external pressure decreases, the helium gas will try to expand and balance its pressure with the atmospheric pressure at that particular height

I have seen that on a movie but not aware of fact why? well Victor Paes Plinio said it right!

This can be done by ideal gas equation but I got a question. I get that the atmospheric pressure decreases so volume increases according to PV=nRT but as you go up temperature also decreases so we should take that into account and so we cannot say volume increases with confidence. Yes, experimentally volume increases but without experimental data we can say for sure that volume increases

As the altitude increases pressure decreases because there are very few air molecules Present in the atmosphere at higher altitude. And due to decrease in pressure the gas volume present in balloon will increase and the balloon will expand.

As it goes up pressure around it decreases thus the ballon inflates therefore volume increase

What if we had a mylar balloon that could not expand? Then the balloon would rise until it was neutrally buoyant, with no volume change. The pressure inside the non-expandable ballon would remain constant.

PV=nRT. where: P=pressure, V=volume, n=moles of gas(Helium), R=Rydberg constant and T=Temperature. For short elevations, T=constant. n=constant because the gas is in the balloon. R=physical constant ... Thus V is inversely proportional to P. Now, the balloon going up encounters a lower P ... and since we have this inverse relationship ... the volume (V) must increase as a result.

The ideal gas law states: pV=nRT Assuming the temperature T to be constant, the balloon‘s volume V will increase as the pressure p gets lower high up in the air.

The pressure outside the balloon changes while the pressure within stays the same so it epands against the balloon as it rises so it expands that gives it a higher volume

The volume of helium inside the balloon increases. Since the balloon is perfectly insulated and properly tied, heat does not effect the balloon, nor there is any air loss. Now as the balloon is released and it rises up the only effect it observes is reduction in atmospheric pressure as the pressure reduces the pressure of helium inside balloon rises and since the balloon is tied properly air can not dispense thus increases the volume.

First recall that density = mass/volume. Because the mass of the balloon is fixed, a decrease in volume corresponds to an increased density. This would actually cause the balloon to come back down, which doesn't happen, so the volume cannot decrease. Similarly, a constant volume corresponds to a constant density. This means that the balloon will rise until it reaches an altitude where its density matches the air and stays there. This also is inconsistent with reality, so the volume cannot stay constant. Therefore, it must increase.

This is not a solution, but a question. Would the same thing happen if the balloon were made of plastic or cardboard even? assuming it still able to float up. now that I'm think about it, how come spaceships don't expand or explode when going into space?

Boyle's Law, right?