Seeking answers to science, scientific questions, seeking answers

c. It often rains in Wenzhou, and there is more water vapor indoors, and when the temperature drops, the water vapor liquefies into water droplets.

The formula for output power and engine power p = fv problem;

The second problem can be solved by combining the ups and downs of the object condition, Archimedes' law formula;

Solution: (1 with a total mass of 500 kg) City Ant" car occupies 2 is the total weight of the vehicle, during operation, by the resistance o4 times, so.

f = g = = 2000n, traction f is at least equal to drag f therefore, power p = fv = 2000 5 = 10000w;

A: The engine with output power is at least 10000W. We're ready; > (2) sees the object floating under the condition represented by the formula of the car with the principle of Archimedes, and in combination with its own gravity equal to the buoyancy of water:

Buoyancy force on the car: F float = water, gravity G2 3V car: g mg = 500 kg of 10n kg = 5000n

Water g2 3v = 5000, the solution is: v = cubic meter, a: total volume at least cubic meter br >

I wish the landlord a progress in learning, you o(o

This is because sodium bicarbonate is a substance that absorbs carbon dioxide.

The diagram will discharge water, and there are plants, indicating that the bottle produces and disperses substances that will not be absorbed by sodium bicarbonate, which means that it is called oxygen.

Different colors of light produce different oxygen and drip out different amounts of water.

There will be CO2 in the water, which will not be completely absorbed, so the intention of sodium bicarbonate is that if it is CO2, then the bucket will be absorbed, which is the meaning. And in the book, the only thing about the color of light is photosynthesis.

The effect of respiration is regulated by temperature, changing to bright moisture, O2

In the question, the temperature is unchanged, the oxygen in the nuclear width is sufficient, the oxygen produced by the imitation water is sufficient, and the oxygen produced by respiration is unchanged, so the oxygen produced by photosynthesis under different lighting conditions is considered, which is the choice 2

Solute: 1*6%, solvent 99*94%.

The mass fraction is: 1*6% (1*6%+99*94%)

ab: Ice and ice water have the same weight, help the mass, and finally melt into water, so the volume after water is the same, so h1=h2

ad：1.If the volume of ice is the same, then the volume of ice in D is smaller, and the liquid level height is the same, so the liquid in D is larger than the volume of water in A, then after turning into water, H4> If the volume of liquid is the same, in order to maintain the same liquid level height, the ice in D must be more than in A to discharge the same volume, so after turning into water, it is still the liquid level in D (multiple-choice special value method, any one explanation can be taken).

ac：1.If the volume of ice cubes (containing iron) is the same, then C is heavy, and there is more liquid discharged in C, so the original water in C is less, and the ice cubes in C contain iron, and the density of iron is greater than that of water, so after the ice is turned into water, the volume in C increases less, and the comprehensive two questions are scored, H3 "If the volume of liquid is the same,,,same as the second step above) choose A

There seems to be a lack of condition: the volume of ice cubes in the four containers must be equal.

The judgment is based on the fact that the liquid level height after melting with the largest volume floating on the water surface is the highest, and the density difference between the liquid with the largest volume on the liquid surface and the liquid below is larger.

Obviously, h4>h1>h3, and for wood in the ice, it depends on what kind of wood.

Some wood has a higher density than water, some are lower than water, if the density is lower than water, the density data of wood in 2 and liquid in 4 are needed to judge the size of H2 and H4; If 2 is wood with higher density than water, then choose c, i.e., h4 h1 h2 h3.

(1) Lower.

2) The syringe has the length of the graduated part L, the cross-sectional area of the syringe S, and the number F of the spring dynamometer at the moment when the piston is pulled out of the syringe

3）10（p0－fl/v）/△p

Solution: The atmospheric pressure at the top of the mountain p=f s=f (v l)=fl v The pressure difference between the summit and the foot of the mountain = p0 p=p0 fl v The relative height of the summit = (p0 fl v) p 10 m = 10(P0 fl v) p m.

4) Small.

12, 32 80000 small solution: the atmospheric pressure on the suction cup f = g = mg = kg 10 N kg = 32 N Measured value of atmospheric pressure p = f s = 32 N (4 10 to the 4th power) square meter = 80000 Pa.

If there is still gas in the sucker, the measured value of the atmospheric pressure = the actual value of the atmospheric pressure The pressure of the gas in the suction cup, so the measured value of the atmospheric pressure is smaller than the actual value.

The output power of the engine can be solved by the formula p=fv of the power;

The second problem can be solved by combining the sinking and floating conditions of the object with the formula of Archimedes' principle.

Solution: (1) The total mass of the "urban ant" car is 500 after carrying two people, and the resistance of the car during operation is 4 times the total weight, so.

f=, traction force f is at least equal to drag f, so power p=fv=2000 5=10000w;

A: The output power of the engine is at least 10000w;

2) According to the floating conditions of the object, the buoyancy of the car in the water is equal to its own gravity, combined with the formula of Archimedes' principle, it can be known that the maximum buoyancy of the car: F float = water G2 3V, the gravity of the car:

g=mg=500kg 10n kg=5000n, then: water g2 3v=5000, solution: v=, answer: its total volume is at least.

I wish the landlord a good progress in his studies

Solution: (1) The total gravity of the "urban ant" car after carrying two people: g object = mg = 500kg 10n kg = 5 103n

The resistance of the "urban ant" car during operation: f = object =

The output power of the engine of the "Urban Ant" car is at least: P=FV=2000N5M S=10000W;

A: The output power of the engine is at least 10000w;

2) When the "Urban Ant" concept car floats on the surface of the water, it has: F float = g object = water g(1-1 3)v;

The variant yields: v=g, water, g(1-1, 3) =5, 103n) =;

A: Its total volume is at least.

1. The crescent moon always appears in the (west) side of the sky.

2. There is a celestial body in the solar system that likes to "lie down", which is Neptune.

3. The earth carries us around the sun at a speed of about 30 kilometers per second.

4. The formation of the four seasons on the earth: due to the rotational movement of the earth, the height of the sun at noon and the length of the day change with time. Summer is the time of year when the sun is at its highest and the days are longestWinter is the season of the year when the sun height is lowest and the length of the day is the shortest, and spring and autumn are in a transitional state.

1.The seasons are different, between southwest and northwest.

2.Neptune.

3.kilometers in seconds.

1.The seasons are different, between southwest and northwest.

2.Neptune.

3.kilometers in seconds.

The orbit of the spherical ellipse, sometimes close to the sun, sometimes far from the sun!