Can Increasing Helium Density Affect Payload in Space?

[MrInventive]

Homework Statement

A spherical balloon has a radius of 7.15 m and is filled with helium. How large a cargo can it lift, assuming that the skin and structure of the balloon have a mass of 930 kg? Neglect the buoyant force on the cargo volume itself.

Relevant Equations

p =m/v density
P = F/A
F = ma

I don't even know where to start...
could you please show me step by step

 

[etotheipi]

What does Archimedes' principle state?

It's customary that you show an attempt before any more help can be given.

 

[Adesh]

Let me give you some hint. Air will act as a fluid, you don’t have to neglect the effect of air as we normally do in mechanics problem.

Can you solve this question: A spherical body of radius $7.15~m$ and mass $930 ~kg$ is in equilibrium inside the water. What are the forces acting on the sphere?

 

[MrInventive]

The Atmosphere and gravity because of the mass of both the fluid and the balloon

 

[MrInventive]

What does Archimedes' principle state?

It's customary that you show an attempt before any more help can be given.

Hello Sorry for the late delay...I lost the website. here's my work

 

[haruspex]

Hello Sorry for the late delay...I lost the website. here's my work

Ok, that's a diagram, but please state Archimedes' principle.

 

[MrInventive]

If an any object is in a fluid (or partially )... there is a buoyant force that will push it...this force is equal to the amount of that liquid displaced.

 

[etotheipi]

this force is equal to the amount of that liquid displaced.

What do you mean by amount?

 

[haruspex]

If an any object is in a fluid (or partially )... there is a buoyant force that will push it...this force is equal to the amount of that liquid displaced.

It is equal to the weight of the fluid displaced.
Ok, so what fluid is being displaced by the balloon and what is its weight?

 

[MrInventive]

well I guess its in air so...that's about it. its density is 1.29 kg/m^3

weight is m*g
m = pV...i get lost here

 

[haruspex]

well I guess its in air so...that's about it. its density is 1.29 kg/m^3

weight is m*g
m = pV...i get lost here

You seem to have all the pieces. You know the volume of air displaced, its density, and the equations leading to its weight. Just put it all together.

 

[Marco Noguez]

Hello Sorry for the late delay...I lost the website. here's my work

Be careful about helium's density and its units. I would advise you to check on your textbook about both density and Archimedes principle concepts.

 

[MrInventive]

You seem to have all the pieces. You know the volume of air displaced, its density, and the equations leading to its weight. Just put it all together.

ok...i'll try

 

[MrInventive]

Be careful about helium's density and its units. I would advise you to check on your textbook about both density and Archimedes principle concepts.

Thank you...i'll look at that

 

[MrInventive]

ok...i'll try

You seem to have all the pieces. You know the volume of air displaced, its density, and the equations leading to its weight. Just put it all together.

I hope this is adequate... I have more questions by the way. Is it OK if i post them?

 

[rephael]

hy.
buoyancy force = air dencity*spher volum*gravity const=1.15*1530*9.8=15000 n
weight force= m*9.8 = 930*9.8=9115 n
helume wight - neglebl
max weight can be load= (15000-9115)/9.8=600 kg

 

[haruspex]

I hope this is adequate... I have more questions by the way. Is it OK if i post them?

You have a sign error. It should be obvious that increasing the density of helium will not result in a greater payload.
In addition, you seem to have a numerical error somewhere in the final step, but I cannot tell where it is.