Aspherical balloon is made from a material whose mass is 3.00 kg. the thickness of the material is negligible compared to the 1.50 m radius of the balloon. the balloon is filled with helium at a temperature of 305 k and just floats in air, neither rising nor falling. the density of the surrounding air is 1.19 kg/m3. find the pressure of the helium gas assuming it is ideal.

To solve the problem it is necessary to apply the definition of Newton's second Law and the definition of density.

Density means the relationship between volume and mass:

While Newton's second law expresses that force is given by

F = ma

Where,

m = mass

a= acceleration (gravity at this case)

In the case of the given data we have to,

In equilibrium, the entire system is equal to zero, therefore

Where,

Weight of balloon

Weight of helium gas

Bouyant force

Then we have,

Replacing the values we have that

Now by ideal gas law we have that

But the relation \frac{n}{m} is equal to the inverse of molar mass, that is

Therefore the pressure of the helium gas assuming it is ideal is 0.61Mpa

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia