Physics 3-1 formula

Physics 3-1 formula

The minimum amount of charge is called "elementary charge" E = 1.6 * 10-19c, the amount of charge carried by an electron is 1E2, Coulomb's law f = kqq / r2 K: electrostatic force constant Q: source charge Q: trial charge 3, electric field intensity (vector) e = f / Q = KQ / R2, the direction of E and positive charge are in
What is the general formula of physical w (online waiting)
Is it w = FS or w = GH?
Is not w always w = FS or w = GH
W = GH is derived from the former (F = gravity g, s = height h)
At the same time, w = Pt, in electricity, w = Pt = uit
W = FS is only suitable for uniform motion (including free falling body), w = GH is only suitable for free falling body
W total = w useful + W extra
W = FS is its definition, and any other formula can be derived from it.
The kinetic energy theorem w = ek2-ek1 or w = FS = Pt can be used in kinematics
Electricity w = Pt = uit = I square RT = (U square / RT)
The object moves upward in the direction of the force, w = GH
When the object moves on the inclined plane, w = FS
Physical formula u = q + W
In physics, if q is greater than 0, is it endothermic or exothermic? If W is greater than 0, is it doing positive work or something
This is the formula of the first law of thermodynamics. U is the internal energy, q is the heat, W is the work. It is generally stipulated that Q is greater than zero in heat absorption, q is less than zero in heat release, W is greater than zero in (positive) work, W is less than zero in (positive) work
Under what conditions do we use the formula w = GH in physics
W=FS
It's the original formula
When lifting the weight in the vertical direction, the work done by the pulling force is as follows:
W=FS=GH
The unit of work is Joule
As long as the work is done by gravity, h is the difference between the two points.
When only gravity does work, w = GH
As long as gravity exists, we can use it to work out the work done by gravity on an object, where h = hmend-hmend
On all the formulas of physical electricity
1. Current intensity: I = q electric quantity / T
2. Resistance: r = ρ L / s {ρ: resistivity (Ω? M), l: conductor length (m), s: conductor cross-sectional area (M2)}
3. Ohm's Law: I = u / R
4. Joule's Law:
(1) , q = i2rt universal formula)
(2) , q = uit = Pt = UQ, electric quantity = u2t / R (pure resistance formula)
5. Series circuit:
（1）、I＝I1＝I2
（2）、U＝U1＋U2
（3）、R＝R1＋R2
(4) U1 / U2 = R1 / R2 (partial pressure formula)
（5）、P1/P2＝R1/R2
6. Parallel circuit:
（1）、I＝I1＋I2
（2）、U＝U1＝U2
（3）、1/R＝1/R1＋1/R2 [ R＝R1R2/(R1＋R2)]
(4) I1 / I2 = R2 / R1 (shunt formula)
（5）、P1/P2＝R2/R1
7 constant resistance:
（1）、I1/I2＝U1/U2
（2）、P1/P2＝I12/I22
（3）、P1/P2＝U12/U22
8 electric power:
(1) , w = uit = Pt = UQ (universal formula)
(2) W = i2rt = u2t / R (pure resistance formula)
9 electric power:
(1) , P = w / T = UI (universal formula)
(2) , P = I2R = U2 / R (pure resistance formula)
All formulas of Physics
Junior high school: speed V (M / s) v = s / T
S: distance t: time
Gravity g (n) g = mg
m: Quality
G: acceleration of gravity, constant, 9.8n/kg or 10N / kg
Density ρ (kg / m3) ρ = m / V
M: mass
V: Volume
The direction of resultant force F (n) is the same: F = F1 + F2
Opposite direction: F = F1-F2, when the direction is opposite, F1 > F2
Buoyancy f floating (n) f floating = g object - G view g view: gravity of object in liquid
Buoyancy f floating (n) f floating = g object
This formula is only applicable to floating or floating objects
Buoyancy f floating (n) f floating = g row = m row g = ρ liquid GV row
Row G: the gravity that displaces the liquid
M row: the mass of liquid in row
ρ liquid: density of liquid
V-row: volume of liquid discharged (i.e. volume immersed in liquid)
Balance condition of lever f1l1 = f2l2f1: power L1: power arm
F2: resistance L2: resistance arm
Fixed pulley f = g
S = HF: the tension on the free end of the rope
G object: the gravity of an object
S: the distance that the free end of the rope moves
H: the distance the object rises
Moving pulley f = (g object + G wheel) / 2
S = 2hg object: the gravity of an object
Wheel G: gravity of moving pulley
Pulley block f = (g object + G wheel)
S = NHN: the number of segments of the rope passing through the movable pulley
Mechanical work w (J) w = FS
F: force
S: the distance to move in the direction of the force
Useful work W has = g matter H
Total work w total w total = FS when the pulley block is placed vertically
Mechanical efficiency η = Wye / wtotal × 100%
Power P (W) P = w / T
W: work
T: time
Pressure P (PA) P = f / S
F: pressure
S: stressed area
Liquid pressure P (PA) P = ρ GH
ρ: density of liquid
H: depth (vertical distance from the liquid surface to the desired point)
Heat Q (J) q = cm △ t
C: specific heat capacity of substance
M: mass
Δ T: change value of temperature
Fuel emission
Q (J) q = MQ
m: Quality
Q: calorific value
Common physical formulas and important knowledge points
I. physical formula (unit) formula remarks formula deformation
Series circuit current I (a) I = I1 = I2 = The current is equal everywhere
Series circuit voltage U (V) u = U1 + U2 + The series circuit acts as a voltage divider
Series circuit resistance R (Ω) r = R1 + R2 +
Parallel circuit current I (a) I = I1 + I2 + The main current is equal to the sum of the branch currents (shunt)
Parallel circuit voltage U (V) u = U1 = U2 =
Parallel circuit resistance R (Ω) 1 / r = 1 / R1 + 1 / r2 +
Ohm's law I = u / I
The current in the circuit is proportional to the voltage and inversely proportional to the resistance
Current definition formula I = q / T
Q: charge quantity (Coulomb)
T: time (s)
Electric work w (J) w = uit = Pt
U: voltage I: current
T: time p: electric power
Electric power P = UI = I2R = U2 / R
U: voltage I: current R: resistance
Electromagnetic wave velocity and wave propagation
The relationship between length and frequency C = λ ν C: wave velocity (the wave velocity of electromagnetic wave is constant, equal to 3 × 108m / s)
λ: wavelength ν: frequency
Several values to remember:
A. sound propagation speed in air: 340m / sb light propagation speed in vacuum or air: 3 × 108m / S
The specific heat capacity of water is 4.2 × 103J / (kgo ℃)
E. voltage of a dry battery: 1.5vf. Voltage of home circuit: 220V
G. safety voltage: not higher than 36V
Write out the calculation steps and what formula to use
If the mass of 1kg is against the vertical wall, the dynamic friction coefficient between the block and the wall is μ = 0.3, the thrust force perpendicular to the wall acting on the block surface is f = 50 N, and the block is in a static state. If G is 10 m / S2, the friction force on the block is
Because it is still, it is in equilibrium, so f = g = mg = 1kgx10n / kg = 10N
The thrust and friction factors are all deceiving
At rest, friction equals gravity. F=mg=10N
Because it's still, f = mg = 10N
Because the object remains static, the vertical direction FF = g = mg = 10 (n) object does not move, do not consider the dynamic friction coefficient, hope to help you
Because f = μ FN, FN represents positive pressure, so f = 0.3 * 50 = 15N
∵ the block is at rest
In the vertical direction, it is affected by the balance force
And ∵ in the vertical direction, it is subjected to the vertical downward gravity mg, and the equilibrium force with the same magnitude and opposite direction is the static friction force F
∴ f=mg=1×10=10（N）
A: the friction force on the block is 10N.
When a flat bottom bucket with water is placed on the horizontal ground, the total mass of water and bucket is 31.5 & nbsp; kg, the bottom area of bucket is 750cm2, and the water depth is 40cm? (2) If the force of lifting the bucket up is 295n, what are the pressure of the bucket on the ground, the pressure of the bucket on the bottom and the pressure of the water on the bottom? (g = 10N / kg)
(1) The pressure of the bucket to the ground is f = g = mg = 31.5kg × 10N / kg = 315n, the pressure of the bucket to the ground is p = FS = 315n750 × 10 − 4m2 = 4.2 × 103pa. Answer: the pressure of the bucket to the ground is 4.2 × 103pa. (2) at this time, the pressure of the bucket to the ground is F1 = g-fra = 315n-295n = 20n, the pressure of the bucket to the ground is P1 = F1s = 20n750 × 10 − 4m2 = 266.67pa, the pressure of water to the bottom of the bucket is p = ρ, the pressure of water GH = 1.0 × 103kg / m3 × 10N / kg × 0.4m = 4 × 103pa A: at this time, the pressure of the bucket to the ground, the pressure of water to the bottom of the bucket are 20n, 266.67pa and 4 × 103pa respectively
Physical electrical formula
I need to summarize the electrical formula of grade two, including the conversion formula, to be comprehensive
[electrical part] 1 current intensity: I = q charge / T 2 resistance: r = ρ L / S 3 Ohm's Law: I = u / R 4 Joule's Law: (1) q = I & # 710; 2rt (universal formula) (2) q = uit = Pt = UQ charge = u & # 710; 2T / R (pure resistance formula) 5 series circuit: (1) I = I1 = I2 (2) u = U1 + U
I = u / R. the most important thing is that you have to understand and memorize the others by yourself, otherwise just memorizing the formula doesn't work.
Junior high school physics, optics, electricity, heat, acoustics, mechanics knowledge structure is in urgent need of junior high school physics basic physical quantity formula summary, need to help sort out the physical formula and other junior high school physics mechanics, electricity, power, and other formulas
The formula of physical electricity
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)
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=U