A hydrogen balloon, with a net weight of 30n, is filled with 20m and 179; the density of hydrogen is 0.09kg/m and that of air is 1.29kg/m;, G=10N/kg (1) How many objects can fall from the bottom of a hydrogen balloon

A hydrogen balloon, with a net weight of 30n, is filled with 20m and 179; the density of hydrogen is 0.09kg/m and that of air is 1.29kg/m;, G=10N/kg (1) How many objects can fall from the bottom of a hydrogen balloon

1. The weight of hydrogen balloon is P1 = 30n;
2. After filling 20m3 hydrogen, the weight of hydrogen is P2 = 0.09x20x10 = 18N;
3. The buoyancy of balloon in air is f = 1.29x20x10 = 258n;
4. The maximum weight that can be lifted under the balloon is P3 = f-p1-p2 = 258-30-18 = 210n
That is, the balloon can lift 210 cattle or 21 kg of objects

Eighth grade physics problems (Archimedes principle)
What is the buoyancy of air to a 2000 m & sup3; airship near the ground? (the known density of air is 1.29kg/m & sup3; G is 10N / kg)
2. The bottom area of the thin-walled cylindrical container placed on the horizontal table is 100 square meters. The hook of the spring dynamometer focuses on the 10N block. Now the block is immersed in water, and the water surface of the container rises from 16cm to 20cm
(1) Volume of liquid discharged by block G: 10N / kg
(2) Buoyancy on the block
(3) At this time, the indication of the spring dynamometer
The gravity of a metal block in the air is 39n. When it is completely immersed in water, the indication of the spring dynamometer is 34n
(1) The metal block is buoyant by water
(2) The volume of the metal block

In the first question, you may have missed the conditions or there is something wrong with the original question. You need to clearly give the state of the airship in order to have a unique answer. Now there are many possible answers. It depends on the state of the inflatable cabin of the airship
The second question is that the container is 100 square meters low. If this is the case, the liquid level rises by 4 cm after the object is immersed in the liquid. The volume of the immersed object is 100 square meters by 0.04 meters = 4 cubic meters. The buoyancy generated by 4 cubic meters of water is 40000 cattle. How can the object of 10 cattle be immersed in the water? It is obviously unreasonable. So the question is wrong. If you encounter this question in the exam, you can write "the question is wrong", You can get full marks. If you don't give a reasonable result, you will get 0

8. Archimedes principle,
When a copper block with a mass of 89g is hung on the spring dynamometer and immersed in a certain liquid, the indication of the spring dynamometer decreases by 0.08n. What is the density of the liquid?

Because of immersion
Ψ v = m / P = 89g / 8.9g/cm cubic = 10cm cubic (P = density)
F = 0.089n-0.08n = 0.009n
F = PGV = P * 10 * 10 (- 6 power) = 0.009n
Ψ P = 0.9g/cm (cubic)