I m a second year junior high school student, and I have this question when I think about physics

The speed of a black hole is superluminous. At the speed of a black hole, light is invisible. The speed at which a black hole moves is immeasurable, and the rotation speed of a giant black hole is about 45% of the speed of light.

As for the velocity of the force, the force is only the quantity that describes the strength of the interaction between objects, not matter, so there is no velocity, only elastic force, which is the force generated by deformation, so the speed transmitted by deformation is the speed of force, but this is not the same as the concept of the velocity of matter. It is recommended that you lay a good foundation in the second year of junior high school, and your hobby of physics should be praised, but you should also learn the knowledge of textbooks in a down-to-earth manner, and the road is step by step, hehe

Black holes themselves have only two properties: charge and mass, and if they are regarded as particles, they have orbital velocity like other celestial bodies.

Strictly speaking, light is not absorbed by a black hole, but cannot escape once it enters the Schwarzschild radius.

As for gravitational force, it is generally inclined to be explained by the transmission of gravitational waves, which is calculated at the speed of light in the relativistic system, but there are not enough experiments and data to confirm it.

Gravitational force is a force that is independent of velocity, and a gravitational force large enough can bend light because the massive mass bends space.

In addition, I am also a second-year junior high school student, and I think that a deep enough idea needs a solid enough knowledge foundation, and we are just in the beginning stage of learning physics, so it is good to have such an idea, but we can't wait until our knowledge framework is strong enough and perfect enough, right?

In addition, the force, whether it is a contact force or a field force, cannot say what its velocity is, it can be said that the magnitude of a force is 5n, but have you ever seen that the speed of a force is 1000m per second? It's like not being able to say what color a sound wave is.

It is recommended that you go to the popular education post bar and watch the science and education film

Textbook for the second year of junior high school: Force is the interaction between objects that can change the state of motion of objects.

Velocity: A physical quantity that indicates how fast or slow an object is moving.

You probably mean the velocity of the object after the gravitational force makes the object move... This is related to the gravitational force, and the speed is different at different times.

But the speed of light is a constant, and the velocity synthesis of classical mechanics does not apply at the speed of light.

I'm a junior high school student, and I envy you for having the potential to be a scientist...

It is indeed very good that a sophomore junior high school student can ask this kind of question, and this idea alone is incomparable to many people, which is worthy of praise! As a college student, I'm sorry I can't.

The velocity of a black hole? I guess it's the escape speed.

A black hole can draw light into it because it has an infinite gravitational pull.

You're talking about gravity? Does gravity have velocity...

Because scientists nowadays are rubbish.

1.When I woke up in the morning, I saw white frost on the road, because the water vapor in the air directly changed from gas to solid, which we call condensation. 2.

Solar Eclipse: This one is because light travels in a straight line. Part of the moon blocks the light that the sun reaches to Earth.

3.Reflection on the surface of the lake. This is because of the reflection of light.

4.Why do you see lightning first and then hear thunder when thunder: First of all, lightning and thunder are carried out together, but the speed of light propagation in the air is fast and the speed of sound in the air is fast.

5.Why does it rain. The water vapor above the clouds solidifies into Xiaoice crystals, which melt into water as it descends.

6.Melting snow is colder than snow. This is because the snow melts and absorbs the surrounding heat, which lowers the surrounding temperature.

3. The pressure on the whole wall is 30 N, the frictional force on object A is 15 N, and the pressure on the wall is perpendicular to the wall.

The frictional force experienced by object A is the force opposite to the direction of motion of A vertically downward (the force that hinders the downward motion of A).

The pressure on the wall is 30n

Object A does not slide downward, so the maximum static friction it experiences is its own gravitational force, which is 15N

1. In fact, there is a current through the original resistance when the short circuit is short-circuited, but because I is inversely proportional to R, and the resistance of the wire is much smaller than the original resistance, so that most of the current passes through the wire.

2. The principle of the bulb is that the tungsten filament heats up to an incandescent state to produce light. Its brightness is related to temperature (not proportional, but the higher the temperature, the brighter the light), and the temperature is determined by the heating power, which p=r(i 2), so the higher the temperature, the greater the resistance, and the brighter the bulb.

1. Because he idealized the circuit, he thought that the resistance of the wire was 0. If the wire resistance is not 0, there is still a small current passing through the resistor in parallel with the wire during a short circuit.

2. "The higher the temperature, the greater the resistance", which corresponds to the filament of ordinary incandescent bulbs, but the brighter the bulb, it is not necessarily, and the brightness will not change significantly for the general situation of a certain voltage.

1. The conductor has a certain resistance, and the resistance of the general electrical appliance is large, and the resistance of the wire is very small, and the resistance of the wire (laboratory) is not more than 1m, and the resistance is close to 0, and there is almost no obstacle to the current. When a short circuit occurs, the wire is connected in parallel with the electrical appliance, and the branch where the electrical appliance is located obstructs the current, while the branch where the wire is located is not obstructed, so the current will not pass through the electrical appliance, but all of it will flow back to the negative pole of the power supply through the wire.

2. The higher the voltage at both ends of the small bulb (not too high, otherwise it will burn out), the greater the current through it, the brighter the bulb, resulting in an increase in the temperature of the filament, so the resistance increases, of course, the increase is not very large.

Let me explain them to you individually.

1。When the short circuit is actually the resistance and a wire in parallel, in fact, there is still a current on the resistor at this time, but because of the relationship between the parallel shunt, the current i = u r, u or r The voltage at both ends is unchanged, so the resistance is small, the current is large, because the wire resistance is very small, compared with the resistance of the access circuit, the difference is more than a few orders of magnitude, so the current of the wire is very large, and it is also a difference of several orders of magnitude, so we can approximate the current passing through the resistor r is 0, ignoring the current on r, i.e. a short circuit directly through the wire.

2。You're talking about a circuit in which a small bulb and a sliding rheostat are connected in series.

Because the resistance on the small bulb becomes larger, the proportion of the partial voltage in series becomes larger (u=i*r, the larger the series partial voltage, the larger the r, the greater the distributed voltage), so the more power on the bulb, so the brighter, this is only a qualitative analysis. Specifically, you can quantitatively analyze the relationship between the change of lamp resistance R lamp and the actual power p through P=I *R lamp and I=U power supply (R lamp + R sliding rheostat).

When the short circuit is shorted, the wire and the electrical appliance are connected in parallel, because the resistance r on the wire is much smaller than the resistance r of the electrical appliance, and the smaller the resistance when paralleling, the more shunts, so the current almost flows through the wire.