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A sliding rheostat slide p when moving to the right sliding rheostat resistance increases, so the total resistance increases, the total current decreases, so the ampere representation number becomes smaller, the lamp becomes dim. The voltmeter measures the voltage of the sliding rheostat, which is equal to the voltage of the supply voltage minus the lamp. Because the voltage of the supply does not change, the voltage of the lamp decreases, so the indicator of the voltmeter becomes larger. Choose A

a) Volts indicate that the number becomes larger and the light becomes dimmed.

The voltmeter measures the voltage of R, and when R shifts to the right, the resistance of R connected to the circuit becomes larger, causing the total resistance to become larger, and the total current becomes smaller, so the power of lamp L becomes smaller (P=I 2R, I becomes smaller, and R does not change), so it becomes darker.

The voltmeter measures the voltage of r, which is equal to the voltage of the mains voltage minus the voltage of the lamp. Because the supply voltage does not change, and the total current decreases, the voltage of the lamp decreases, so the voltmeter indicates that it becomes larger.

According to the law of "concatenation, reversal and conjunction", it is known that option A is correct.

Select A, as can be seen from the figure, the voltmeter measures the voltage at both ends of the varistor, and the ammeter measures the total current. The power supply voltage does not change, the electric bond is closed, and the slide moves to the right. The resistance value of the rheostat access circuit increases, the voltage division increases, and the indication of the voltmeter increases. It is obtained by i=v r, v is fixed r to increase, the current becomes smaller, and the ampere representation number becomes smaller, that is, the current through the bulb becomes smaller, and the bulb becomes darker and a is selected

This problem is good as long as you understand the resultant force, because it is the cylinder expansion that produces thrust on the piston, so the resultant force is acting on the piston and downward, generating two components, one along the direction of the connecting rod F1, the other perpendicular to the connecting rod F3, F3 can be decomposed to get the pressure on the cylinder wall, F2 = F*Sin30°*Cos30°.

PhyoceanTW is a bit of a problem, the thrust of the connecting rod AB should be the reaction force of F1. The pressure is generated by the action of the tie rod, so the reaction force of the pressure should be a component of the tie rod. So the diagram should be drawn like this.

Then f1=f cos30°; f2=f×tan30°

Utilize the principle that the contours of the Sun and Moon coincide during a solar eclipse.

There is a solar radius Moon radius = Earth-Sun distance Earth-Moon distance.

Therefore, the radius of the sun = the radius of the moon * (the distance between the earth and the moon) is calculated by itself.

1 The invariance of the speed of light in a total vacuum is a basic assumption of special relativity, which is basically in a similar axiomatic position in special relativity (basic, in fact, strictly speaking, it is a theorem, which can be derived from another fundamental assumption (the principle of relativity)). First, experiments tell us so; Second, according to the principle of relativity, if Maxwell's equations are required to be true for any inertial frame, the speed of light must be constant. If you want to ask deeper, then you have to pursue a deeper theory than the theory of relativity, just as in Euclidean geometry, you can't ask why the straight line between two points is the shortest.

As for how this makes the theory of relativity self-consistent, first of all, inertial frames must be defined in the theory of relativity. In Newtonian mechanics, as long as an inertial frame can be defined (the frame of reference in which Newton's first law is true), then the frame of reference that moves at a uniform speed relative to it is an inertial frame; In the theory of relativity, the relative velocity between two "legal" inertial frames is less than c, and the theory of relativity has a formula for velocity synthesis that guarantees that even if A moves to the left with respect to me and B moves to the right with respect to me, the velocity of B with respect to A is still less than C, so that in such a system, the photon is not used as a legitimate frame of reference. As a zero-mass (stationary) particle, the photon has a velocity c in all of the above-mentioned "legal" frames of reference (this is also true for other zero-mass particles, such as gluons and gravitons, so you can argue that a zero-(stationary) mass particle is fundamentally different from a mass substance (such as the person you mentioned), but not all descriptions are exactly the same, and the transformation frame of reference also has an effect on these particles.

For example, the energy of a photon in two reference frames (known by the photoelectric effect, i.e., equivalent to the frequency of the photon) is not the same (Doppler effect), and when the relative velocity between the reference frames is angled to the direction of light propagation (in either of the reference frames), the direction of light propagation seen by the two reference frames is not the same (optical travel difference).

There are two principles of relativity: one is the principle that the speed of light does not change, and the other I forgot. The principle of invariance of the speed of light is an experimental conclusion (Michelson-Morey experiment) and is equivalent to an axiom in mathematics.

Because the theory of relativity is talking about high-speed motion, ordinary people can't experience it personally, so there is no experience to refer to, so it's normal to not figure it out, and rookies like me can only rely on formulas to calculate and draw conclusions.

Of course, I don't know how the real masters understand the theory of relativity, I'm just a rookie.

It should be a relationship between the theoretical hierarchy.

The theory of relativity applies to motion less than the speed of light The speed of light is the limit and the limit is required to be fixed.