There are two points Mn on the line AB, point m divides AB into two parts of 1:2, point n divides AB into two parts of 1:3, and Mn = 2cm

There are two points Mn on the line AB, point m divides AB into two parts of 1:2, point n divides AB into two parts of 1:3, and Mn = 2cm

Point m divides AB into 1:2 and point n divides AB into 1:3
∴AM=1/3AB,AN=1/4AB
∴MN=AM-AN=1/12AB
∵MN=2㎝
∴AB=2×12=24㎝

If Mn = 2cm, then the length of AB is 9 (). Write the process of solving the problem
If Mn = 2cm, the length of AB is 9 ()
Write out the process of solving the problem

The answer is 70 cm
Let am = 2A; MB = 3A; then AB = 5A
An = 3B; Nb = 4B; then AB = 7b
So AB = 5A = 7b:
a=7/5b
MN=AN-AM=2cm
That is: 3b-2a = 2cm
3b-2×7/5b=2cm
The solution is: B = 10cm
AB=7b=70cm

As shown in the figure, there is a vertical baffle on the inclined plane with an inclination of 30 degrees. Between the baffle and the inclined plane, there is a smooth ball with a weight of 20n at rest. Find out: (1) the supporting force of the inclined plane on the ball; (2) the elastic force of the vertical baffle on the ball

The force analysis of the ball is as shown in the figure: because the smooth ball is in a static state under the copoint force, the resultant force of the smooth ball is 0. The FN1 is decomposed in the horizontal and vertical directions. According to the condition of the copoint force balance, the elastic force of the ball to the inclined plane FN1 = gcos30 ° = 4033n; the elastic force of the ball to the baffle FN2 = gtan30 ° = 2033n. A: the elastic force of the ball to the inclined plane is 4033n, and the elastic force of the ball to the baffle is 2033n

What is the power of household appliances
Give as many examples as possible

The TV is about 300 watts of 30 inch non LCD. The LCD should be smaller
The washing machine is about 800-1000 watts (small)
If the air conditioner is station type, it will cost electricity. My unit is 2620 watts. The one on the wall is about 1600 watts
Fluorescent lamps are longer for household use, 30 and 40 watts
Computer host is not fixed, depending on the use. About 150-300 watts
(power consumption) LCD 30-50 watts. Flat 100 watts
The refrigerator is not fixed. It depends on how you use it. If the refrigerator doesn't break, it's basically between 100-200 watts
And the night light. The small one is one watt
Induction cooker about 1200 (medium fire) microwave oven check not much
It's nothing in the world. 1000 watt electric appliances burn for one hour

Pythagorean theorem in the second grade of junior high school, how can the number be squared with speed? It's like getting 225. I know its square is 15. How can we calculate the speed?

This has to memorize the general middle school need to recite 1-20 square, so the problem is very fast
Generally, the number of Pythagorean shares does not exceed 20, even if the number exceeds 20, it is also multiple. For example, 3, 4 and 5 are Pythagorean shares
The 30, 40 and 50 are also Pythagorean numbers. Generally, the Pythagorean numbers used are all within 20, so square 1-20
It's easy to get down

When a power supply is connected with 8 ohm resistance, the current passing through the power supply is 0.15A, and when it is connected with 13 ohm resistance, the current passing through the power supply is 0.10a. Calculate the electromotive force and internal resistance of the power supply

Let the electromotive force of the power supply be u and the internal resistance be r
U=（8+R)*0.15
U=（13+R）*0.10
have to
U = 1.5V
R = 2 Ω
Listen well in physics class!

Natural numbers are arranged according to the rule as shown in the figure. The fourth row and the third column of the number 14 are recorded as (4,3). Then what is the number 127 recorded as?
1 2 5 10
4 3 6 11
9 8 7 12
16 15 14 13
Teach me the method

(6,12)
Find the rules first,
First write 1,
Write around 2, 3, 4
5, 6, 7, 8, 9,
You can see that they all end in squares
The square before 127 is 121 (the square of 11)
So when I write 121, there are 11 rows and 11 columns
The remaining six will start with the first one in column 12
It's on line six
So it's (6,12)

When the voltage at both ends of a certain resistor is 4V, the electric power is 1W; when the voltage at both ends of the resistor is 2V, the electric power is ()
A. 1WB. 2WC. 0.5WD. 0.25W

The resistance value of the constant value is: r = u21p1 = (4V) 21W = 16 Ω; when the voltage at both ends of the constant value resistor is 2V, the electric power of the constant value resistor is: P = u22r = (2V) 216 Ω = 0.25W

2 times 2 / 15 + 2 / 15 △ 0.8

Hello
2 times 2 / 15 + 2 / 15 △ 0.8
=4/15+2/15x5/4
=4/15+1/6
=13/30
Do not understand, you can ask, if helpful, remember to adopt, thank you, I wish learning progress!

Close the switch s, the reading of ammeter is 0.3 A, and the reading of voltmeter is 3 V. what is the resistance value of resistance R1? If R1 is replaced by resistance value of 15 ODR R2, what are the readings of ammeter and voltmeter? (the power supply voltage remains unchanged) detailed calculation steps are required!

Do you have a picture? It's hard to do without a picture