Ask a somewhat boring physics question and the experts come in and help me analyze it

I think it's from the perspective of an inertial frame. The fly and the car are in the same frame of inertia, so the fly and the car have the same velocity, and its velocity is very large relative to the ground, but this velocity is not generated by its own power. It's like the person in the car has the same speed as the car.

The speed at which the fly flies should be based on the car as a frame of reference, as long as its forward velocity is not less than zero relative to the car, it will not reach the rear glass of the car.

The fly should also be accelerated to 100 speeds

It makes sense why you don't need to run at 100 in the car.

You can do an experiment with a levitating balloon

Put the balloon in a moving car and see if it floats back, which I personally don't think it will be

The answer is as it was said upstairs: flies and cars are in the same frame of inertia

Consider that the air inside the car is also moving at a speed of 100 kilometers per hour. The flies are pushed by this air, and they only need to move relative to the air, exactly like flying in the room.

Let's say you're constantly walking back and forth in the car. What's your speed? Think of yourself as the fly and you'll understand.

The carriage can be seen as a relatively confined space. I know what you mean, but the kind of situation you're talking about happens in a vacuum. And in real life, there is air, so the air in the compartment will move with the car, and the fly will not go out when it is surrounded by air, so it is really fast after you choose the ground as a reference frame.

It's good for the fly to fly relative to the car, and of course it flies at high speed relative to the ground, and if the car suddenly disappears, it's a big deal because the air resistance slows down.

I don't have a good internet connection and I can't see the map. According to my imagination, analyze it.

This should be a typical type of problem.

Think of the rings and the balls as a system. This system is not subject to external forces in the horizontal direction. Therefore, in the horizontal direction the momentum of the system is conserved, assuming that the masses of the ring and the sphere are m and m respectively, and their horizontal velocity is positive friend ratios v1 and v2 respectively

Then there is m*v1 = m*v2, and v1 = m*v2 m is obtained and the whole process takes time t

Then v1*t + v2*t = l and bring in v1 to get v2*t*(1+m m) = l

The horizontal distance of the ball v2*t = lm (m+m) is similar to this: a boat with a length l and a mass m, and a person with a mass m walks from the bow to the stern of the boat to find the distance the boat moves relative to the surface of the water.

v'=mv/(m+m)

mgh=1/2mv∧2-1/2m∧2v∧2/(m+m)h=1/2mv∧2/(m+m)g

From this, you ask for time t

Then we can find s

Hope to fight or to you have a help empty help (

Use the angle of the two bottom angles of the right triangle of the waist of the brigade ruler to calculate the height.

Because the ice cubes do not melt, if you have read high school books, you should know that the temperature of the ice-water mixture is always zero, and the temperature does not change until the ice cubes are completely melted or completely condensed.

If you remove the condition that "there are ice cubes in it that have not melted", you will choose B.

Because water is more likely to evaporate in sunlight, evaporation takes away the heat in the water, which lowers the temperature of the water.

There should also be an implicit condition in the question, that is, the temperature is the same in the sun and in the shade).

c is the same as the ice-water mixture, and the temperature is 0

Option B, because sunlight accelerates the melting of ice, and the melting of ice is an endothermic process, so the temperature of the water is lower than that in the shade.

I can't see the picture, but the two of them are carrying the front and back points of the lower edge of the box.

At this point, the center of gravity of the object is in the middle of the box. Since the resultant force of the two people is the gravity of the box, and the upward force of the two people should be balanced against the moment of the center point of gravity, so the size of the force = look at the inverse ratio of the distance from the two support points to the center point of gravity. It translates into a geometric problem.

Then draw a similar triangle and use the formula tan(a+45°)=tana+tan45°) 1-tana*tan45°). Because tan a= , tan45°=1

b The force-to-wall ratio is 3:7, so the force ratio is 7:3

Solution: (1)72 5=s).

Then the car stops after seconds.

2) 72-5 3=57 (m-s).

Then the speed of the car at the end of 3s after braking is 57 meters per second.