Er, what's the meaning of "focal radius" in conic curve? What's the formula?

Er, what's the meaning of "focal radius" in conic curve? What's the formula?

The focal radius is the distance from the point on the conic to the focal point
Denoted by R
Ellipse r = a ± ex
Hyperbola r = | ex ± a|
Parabola r = P / 2 + X0

Pressure unit conversion, please convert several units of pressure kg / cm2, MPa, psi, bar, be sure to be accurate

1 MPa = 145 lb / in2 (PSI) = 10.2 kg / cm2 (kg / cm2) = 10 bar = 9.8 ATM 1 lb / in2 (PSI) = 0.006895 MPa = 0.0703 kg / cm2 (kg / cm2) = 0.0689 bar = 0.068 ATM 1 bar = 0.1 MPa = 14.503 lb / in

Conic curve is a difficult problem in multiple-choice questions, how to make a reasonable estimate? Because this kind of questions are very troublesome, and as a multiple-choice question, you can estimate and see the answer from a special angle. I want to ask how to correctly estimate the answer? (especially refers to the difficult questions in the choice, such as the curve type formed by a group of narratives, or two conic curves set together, Ask the range of centrifugal rate, etc.)

I'm also a sophomore in senior high school. I tell you very clearly that 99% of the choices are not for you to calculate in a long way. Conic curve is not difficult. The key to making a choice is to master skills. There are many simple skills of conic curve. It's easy to do them as long as you memorize them, such as focal radius and half path. As for the two conic curves you said, they are set in

Length. Area. Volume. Mass. Time. Rate of progress!

A high-level unit contains a multiple of a low-level unit, which is called the rate of advance between the two units. When rewriting the name of the unit, the rate of advance is used. The method is: the number of high-level single names × the rate of advance = the number of low-level single names; the number of low-level single names △ the rate of advance = the rate of advance of each of the two adjacent units of measurement of high-level single names

Electrical formula of junior high school

1、 Ohm's law part
1. I = u / R (Ohm's Law: the current in a conductor is directly proportional to the voltage at both ends of the conductor and inversely proportional to the resistance of the conductor)
2． I=I1=I2=… =In (characteristic of current in series circuit: current is equal everywhere)
3． U=U1+U2+… +UN (characteristics of voltage in series circuit: in series circuit, the total voltage is equal to the sum of voltage at both ends of each circuit)
4． I=I1+I2+… +In (the characteristic of current in parallel circuit: the current on the main circuit is equal to the sum of the currents in each branch circuit)
5． U=U1=U2=… =UN (characteristics of voltage in parallel circuit: the voltage at both ends of each branch is equal to the power supply voltage)
6． R=R1+R2+… +RN (characteristic of resistance in series circuit: the total resistance is equal to the sum of resistance of each part of the circuit)
7． 1/R=1/R1+1/R2+… +1 / RN (the characteristic of resistance in parallel circuit: the reciprocal of total resistance is equal to the sum of the reciprocal of each parallel resistance)
8. R and = R / n
9. R series = NR (formula for calculating total resistance when n identical resistors are in series)
10. U1: U2 = R1: R2 (relationship between voltage and resistance in series circuit: the ratio of voltage is equal to the ratio of their corresponding resistance)
11. I1: I2 = R2: R1 (relationship between current and resistance in parallel circuit: the ratio of current is equal to the inverse ratio of their corresponding resistance)
2、 Electric power part
12. P = UI (empirical formula, suitable for any circuit)
13. P = w / T (definition, suitable for any circuit)
14. Q = i2rt (Joule's law, suitable for any circuit)
15．P=P1+P2+… +PN (suitable for any circuit)
16. W = uit (empirical formula, suitable for any circuit)
17. P = I2R (compound formula, only suitable for pure resistance circuit)
18. P = U2 / R (compound formula, only suitable for pure resistance circuit)
19. W = q (empirical formula, only suitable for pure resistance circuit, where W is the work done by the current flowing through the conductor and Q is the heat generated by the current flowing through the conductor)
20. W = i2rt (compound formula, only suitable for pure resistance circuit)
21. W = u2t / R (compound formula, only suitable for pure resistance circuit)
22. P1: P2 = U1: U2 = R1: R2 (the relationship between electric power and voltage and resistance in series circuit: in series circuit, the ratio of electric power is equal to the ratio of voltage and resistance)
23. P1: P2 = I1: I2 = R2: R1 (the relationship between electric power and current and resistance in parallel circuit: in parallel circuit, the ratio of electric power is equal to the ratio of their corresponding current and the inverse ratio of their corresponding resistance)

Ask 400 oral arithmetic questions in grade 4,

26 -6 -64 = 20 -64 = -44
10 -80 = -70
27 + 3 -48 = 30 -48 = -18
28 + 12 -32 = 40 -32 = 8
29 + 21 -16 = 50 -16 = 34
30 + 30 + 0 = 60 + 0 = 60
70 + 16 = 86
80 + 32 = 112
90 + 48 = 138
34 + 66 + 64 = 100 + 64 = 164
35 + 75 + 80 = 110 + 80 = 190
36 + 84 + 96 = 120 + 96 = 216
37 + 93 + 112 = 130 + 112 = 242
38 + 102 + 128 = 140 + 128 = 268
= 150 + 144 = 294
40 -30 -140 = 10 -140 = -130
= 20 -124 = -104
42 -12 -108 = 30 -108 = -78
43 -3 -92 = 40 -92 = -52
44 + 6 -76 = 50 -76 = -26
45 + 15 -60 = 60 -60 = 0
70 -44 = 26
47 + 33 -28 = 80 -28 = 52
90 -12 = 78
49 + 51 + 4 = 100 + 4 = 104
50 + 60 + 20 = 110 + 20 = 130
51 + 69 + 36 = 120 + 36 = 156
52 + 78 + 52 = 130 + 52 = 182
53 + 87 + 68 = 140 + 68 = 208
150 + 84 = 234
55 -45 -200 = 10 -200 = -190
56 -36 -184 = 20 -184 = -164
57 -27 -168 = 30 -168 = -138
58 -18 -152 = 40 -152 = -112
59 -9 -136 = 50 -136 = -86
60 + 0 -120 = 60 -120 = -60
61 + 9 -104 = 70 -104 = -34
62 + 18 -88 = 80 -88 = -8
63 + 27 -72 = 90 -72 = 18
100 -56 = 44
65 + 45 -40 = 110 -40 = 70
66 + 54 -24 = 120 -24 = 96
67 + 63 -8 = 130 -8 = 122
68 + 72 + 8 = 140 + 8 = 148
69 + 81 + 24 = 150 + 24 = 174
70 -60 -260 = 10 -260 = -250
71 -51 -244 = 20 -244 = -224
72 -42 -228 = 30 -228 = -198
73 -33 -212 = 40 -212 = -172
74 -24 -196 = 50 -196 = -146
There are answers. And there is a simple calculation process
Copy it quickly

Series and parallel with various electrical calculation formula, how to calculate, make it clear
In all parallel circuits the formula is used

Current: Series I = I1 = I2
Parallel I = I1 + I2
Voltage: Series u = U1 + U2
Parallel u = U1 = U2
Resistance: Series R = R1 + R2
Parallel r = 1 / R1 + 1 / r2 = (r1r2) / (R1 + R2)
When I = u / R, P = UI
P = u & sup2 / r r = u & sup2 / P U amount & sup2 / u real & sup2; = P amount / P real
The series partial voltage is proportional to the resistance: U1 / U2 = R1 / R2
The parallel current is inversely proportional to the resistance: I1 / I2 = R2 / R1
The rest won't ask me

Simple calculation of fractional multiplication
3.2 * 5 / 9 + 6 and 4 / 5 * 5 / 9-5 / 9
2 and 1 / 3 * 3 / 5 + 4 * 2 / 5 + 1 and 2 / 3 * 3 / 5
16 * (3 / 4 + 5 / 9) * 275 / 18 * 6 / 7 + 2 and 1 / 6 * 2 / 72 and 1 / 3 * 3 / 5 + 4 * 2 / 5 + 1 and 2 / 3 * 3 / 5
5 / 18 * 6 / 7 + 2 and 1 / 6 * 2 / 7

3.2 * 5 / 9 + 6 and 4 / 5 * 5 / 9-5 / 9 = 5 / 9 (3.2 + 6.8-1) = 5 / 9 * 9 = 52 and 1 / 3 * 3 / 5 + 4 * 2 / 5 + 1 and 2 / 3 * 3 / 5 = 3 / 5 (2 and 1 / 3 + 1 and 2 / 3) + 4 * 2 / 5 = 3 / 5 * 4 + 4 * 2 / 5 = 4 (3 / 5 + 2 / 5) = 4 * 1 = 416 * (3 / 4 + 5 / 9) * 275 / 18 * 6 / 7 + 2 and 1 / 6 * 2 / 72 and 1 / 3 * 3 / 5 + 4 * 2 / 5 + 1 and 2 / 3 * 3 / 5 =

Imagine that the Chang'e lunar landing spacecraft moves in a uniform circular motion close to the surface of the moon, and the measured period is t. after the spacecraft lands on the moon, the robot uses a dynamometer to measure the instrument gravity with mass m as P. the known constant of gravity is g, and the quantity that can be calculated from the above data is ()
A. The radius of the moon B. the mass of the moon C. the acceleration of gravity on the surface of the moon D. the centripetal acceleration of the moon's uniform circular motion around the earth

A. The gravity of the instrument with mass m measured by the dynamometer of the automatic robot is p, that is, P = mg. According to the universal gravitation equal to gravity, gmmr2 = P, where m is the mass of the moon and R is the radius of the moon. It is studied that the Chang'e-1 lunar landing spacecraft moves in a uniform circular motion close to the surface of the moon. According to the universal gravitation, the centripetal force is provided, and the equation is: gmmr2 = MR4 π 2t2, and ② r = pt24m π2  ③ So a is correct; B. the mass of the moon M = p3t416gm3 π 4 is obtained from ① and ②, so B is correct; C. the gravity of the moon surface is equal to the universal gravitation, and it also provides the centripetal force of the near moon satellite, so gmmr2 = mg = MR4 π 2t2. The radius of the Moon R can be obtained from a analysis, and then the acceleration of gravity g can be obtained from the period, so C is correct; D. the topic of this study is "Chang'e" The "No.1" lunar landing spacecraft is close to the surface of the moon and moves in a uniform circular motion, so it can't calculate the centripetal acceleration of the moon in a uniform circular motion around the earth, so D is wrong

Urgent. Who can give me 20 simple fractions multiplication!
For example, (5 / 3 + 7 / 3) × 9 is simply calculated by using the law of multiplicative distribution!
=5/3×9+7/3×9
=15+21
=31

(1/2+2/3)*6=1/2*6+2/3*6=3+4=7
(2/3+3/4)*12=2/3*12+3/4*12=8+9=17
(1/3+1/4)*12=1/3*12+1/4*12=4+3=7
(1/4+1/5)*20=1/4*20+1/5*20=5+4=9
(2/3+2/5)*15=2/3*15+2/5*15=10+6=16
(3/4+1/2)*4=3/4*4+1/2*4=3+2=5
(10/11+12/10)*110=10/11*110+12/10*110=100+132=232
(2/5+2/7)*35=2/5*35+2/7*35=14+10=24
(3/5+3/7)*35=3/5*35+3/7*35=21+15=36
(4/5+5/6)*30=4/5*30+5/6*30=24+25=49
(5/7+5/8)*56=5/7*56*5/8*56=40+35=75
(8/9+9/10)*90=8/9+90*9/10*90=80+81=161
(11/12+6/5)*60=11/12*60+6/5*60=55+72=127
(9/5+9/4)*20=9/5*20+9/4*20=36+45=81
(4/7+5/6)*42=4/7*42+5/6*42=24+35=59
(3/8+2/9)*72=3/8*72+2/9*72=24+16=40
(1/11+1/15)*165=1/11*165+1/15*165=15+11=26
(1/20+1/30)*60=1/20*60+1/30*60=3+2=5
(2/31+3/62)*62=2/31*62+3/62*62=4+3=7
(11/16+13/32)*32=11/16*32+13/32*32=22+13=35