Please help me summarize it, thank you very much! Detailed

In junior high school physics, the internal resistance of the power supply is not considered, so the voltage at both ends of the default power supply is always the same, if it is more true, you draw the power supply as an ideal power supply plus a resistor, so that the analysis of the voltage of the two sections of the power supply is actually to rise, the specific distribution, according to your equivalent circuit diagram is good.

You write an expression of the total resistance of two resistors in parallel, and then set several sets of data into it yourself, and observe the changes, you will find that it will decrease, so the total current will increase.

1. No return, the voltage size remains unchanged (regardless of internal resistance), and the voltage is still distributed according to the resistance size. When the total resistance increases, the current decreases, and when the total resistance decreases, the current increases.

2。It will increase, like the sum of several numbers, and the sum will increase.

The total voltage does not change with resistance (regardless of internal resistance).

In general, the total voltage is constant, but in the circuit, if there is a power supply, the total voltage is constant. Tandem: the resistance increases, the voltage does not change, the resistance increases, the total current decreases, and the current on each resistor decreases.

Parallel: Similarly, the total voltage remains the same, the voltage of each branch remains the same, the resistance increases, the current decreases, and the total current decreases.

Your question can be divided into two.

Why is the density of water used, the question says that it is Figure B, and Figure B uses water, so the density of water is calculated. (It's really important to read the questions carefully).

How to understand pressure difference.

To understand the pressure difference, we must first understand the pressure. Here I quote the encyclopedia: Pressure - the ratio of the magnitude of the pressure on the object to the area of the force is called pressure.

The symbol is p (pressure), and the pressure is used to compare the effect of pressure, and the greater the pressure, the more obvious the effect of pressure. The formula for calculating pressure is: p=f s, the unit of pressure is pascal (abbreviated as pa), and the symbol is pa.

Then there is the pressure difference, which is the "difference in pressure". Since there is a difference involved, there will be at least two pressures, or more. In order to calculate the pressure difference, it is first necessary to clarify who is being compared, that is, to know whose pressure is compared to whose pressure, and this is not clear, it is impossible to calculate.

There are four groups of pressure differences involved in this question, two of which are directly comparable: air vs. water, air vs. salt water; There are also two groups that need to be compared indirectly: water vs. salt water, and the pressure in the water at different depths.

With this understanding, I believe you will have a deeper understanding of the topic. Feel free to ask.

Solid: 1Measure the mass of the object with a pallet balance, denoted as m;

2.Add an appropriate amount of water to the graduated cylinder, and the volume is v1;

3. Put the cracked celery object into the graduated cylinder lightly, read out the volume, and record it as V2;

4.Then the density of the object is m (v2-v1).

Liquid: 1Measure the mass of the empty graduated cylinder with a tray balance, which is recorded as m12, load the liquid into the graduated cylinder, and measure the total mass of the empty graduated cylinder with a tray balance, which is recorded as m23Read out the number of the graduated cylinder, which is denoted as v

4, then the density of the liquid is (m2-m1) v

Solution: Let the motion time of the object be t

The horizontal motion displacement of the object is x=v0*t

The vertical displacement of the object is y=1 2*g*t 2

Then there is: tan30 = y x

If t=, the height difference between the throwing point and the impact point is y=1 2*g*t 2=complete, it is not convenient to write the calculation result here, you can calculate it yourself.

The idea of this problem is to decompose the motion of an object horizontally and vertically, and combine it with a right triangle to find time.

This is satisfying.

There should be a picture, but there should be no picture. Whether it is left or right. The answer is different. Or two possibilities?

It can be seen that when the object falls to the ground in 1s, then h=1 2 g t 2=5m

v0=2, s=v0 t=

When v0=2, the vertical displacement is , then the angle is 45 degrees.

The electric potential at each point in the space from positive charge to negative charge gradually decreases, but because on the same conductor, the conductor is in electrostatic equilibrium at this time, it is an equipotential body, so the electric potential at the two points is equal, and the electric potential is also equal in the same way. But the proximity to positive charge potential is higher and close to the negative charge potential is lower. So the correct answer is b

15(1) by e=blv0 i=e r=blv0 r, rod movement, 2l effective length l'=l/2

i=blv/2r v=2v0

2) The amount of electricity q passing through the conductor cross-section

q=b(l+l/2)2l/2r=3bl^2/2r=itt=3l/2v0

From the kinetic energy theorem.

w-wa=1/2mv^2-1/2mv0^2 wa=i^2rtw=3mv0^2/2+3b^2l^3/2r(3)t=3l/2v0

Is it the Roller Magnetism? Almost forgot about it, just to take a look.