How Do You Calculate the Buoyant Force for a Stratospheric Balloon?

• nicky670
In summary: That's the right idea. For what substance are you going to find the mass in order to get the buoyant force?For balloon, you will need to find the mass of the balloon first and then use the rho=m/v formula to find the buoyant force.
nicky670
Homework Statement
The figure on the right shows a stratospheric balloon
carrying a payload. The density of helium at 1.0 atm and 15 oC
is 0.168 kg/m3 and the density for air is 1.225 kg/m3. The mass
of the balloon (skin without helium) and the payload is 260 kg.
The volume of the balloon at ground level is 300 m3
Relevant Equations
Upthrust?
I have gathered the formula:
F(Bouyant force) - (Mballoon + Mpayload)g - (Mhelium)g = (Mballoon + Mhelium + Mpayload)a
But i can't seem to figure out what is the buoyant force to find a. Or am i mistaking something?

nicky670 said:
F(Bouyant force) - (Mballoon + Mpayload)g - (Mhelium)g = (Mballoon + Mhelium + Mpayload)a
Ok
But i can't seem to figure out what is the buoyant force to find a. Or am i mistaking something?
Have you covered Archimedes' Principle?

Yes i have.

According to Archimedes' principle, how would you find the buoyant force on a rock of volume V that is completely submerged in water?

Chestermiller
it is the volume of water displaced by the rock that will get you the buoyant force right?
TSny said:
According to Archimedes' principle, how would you find the buoyant force on a rock of volume V that is completely submerged in water?
It will be the volume of water displaced by the rock right? For buoyant force

nicky670 said:
it is the volume of water displaced by the rock that will get you the buoyant force right?

It will be the volume of water displaced by the rock right? For buoyant force
A volume is not a force. What attribute of that volume of fluid?

haruspex said:
A volume is not a force. What attribute of that volume of fluid?
The weight of the volume of water displaced

nicky670 said:
The weight of the volume of water displaced
Yes, that's right. Does this help with finding the buoyant force on the balloon?

TSny said:
Yes, that's right. Does this help with finding the buoyant force on the balloon?
So i use rho = m/v formula to find the mass and then multiply by g=9.8 to get the weight?

nicky670 said:
So i use rho = m/v formula to find the mass and then multiply by g=9.8 to get the weight?
That's the right idea. For what substance are you going to find the mass in order to get the buoyant force?

1. What is a stratospheric balloon?

A stratospheric balloon is a large, high-altitude balloon that is designed to fly in the stratosphere, which is the second layer of Earth's atmosphere. These balloons are often used for scientific research and data collection.

2. How high can a stratospheric balloon fly?

Stratospheric balloons can reach altitudes of up to 120,000 feet (36,500 meters) above sea level. This is approximately three times the height of a commercial airplane flight.

3. What is the purpose of launching a stratospheric balloon?

The primary purpose of launching a stratospheric balloon is to collect data and conduct scientific experiments in the upper atmosphere. These balloons can also be used for testing and calibrating equipment for space missions.

4. How long can a stratospheric balloon stay in the air?

The duration of a stratospheric balloon flight can vary depending on the payload and atmospheric conditions, but they can typically stay in the air for several hours to a few days. Some specialized balloons have been known to stay aloft for weeks or even months.

5. How does a stratospheric balloon stay afloat?

Stratospheric balloons stay afloat by using helium or hydrogen gas to provide lift. The gas is contained in a large envelope, which is usually made of a thin, lightweight material such as polyethylene or polyester film. The balloon's altitude is controlled by releasing gas through a valve or by using a ballast system to adjust the weight of the payload.

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