Do you speak English? If so I can help you in the comments
Assuming that the densities of the gases are:
density of air, ρ1 = 1.29 kg / m^3
density of helium, ρ2 = 0.179 kg / m^3
Since buoyant force and weight are two forces that are in
opposite direction (buoyant force is up while weight is down), therefore equate
the two:
buoyant force = weight
m g = (800 + m1) g
where m is the mass of buoyancy, g is gravity and m1 is
the maximum mass of the cargo
m = 800 + m1
We know that mass is also expressed as:
m = ρ V
where ρ is density of gas and V is volume of the sphere
Since there are two interacting gases here, therefore m
is:
m = (ρ1 – ρ2) V
Therefore:
(ρ1 – ρ2) V = 800 + m1
(1.29 – 0.179) (4π/3) (8.35m)^3 = 800 + m1
2709.33 = 800 + m1
m1 = 1,909.33 kg
Answer:
<em>The best explanation is that the first person is grounded to the earth, and his/her body either draws up negative charges from the earth, or tend to conducts negative charges to the earth, depending on the charge on the balloon.</em>
Explanation:
The earth is an infinite store for charges. In the first case where the second person brings a negatively charged balloon towards the first person, the negative charges on the balloon induces the first person's body to tend to attract the negative charges on the balloon through the first person's body to the positive charges within the earth. In the second case when again a positively charged balloon is brought near the first person's hair, the positive charges on the balloon induce the first person's body into drawing up negative charges from within the earth. This charges, and their opposite induced charges, create an attractive force between the hair strands and the balloons.
