I found two physical formulas. I don't know if they are the same One is Laplace's tension formula, P = 2T / R, P is pressure, t is tension The other is the surface tension P = 2A / R, where p is the pressure and a is the surface tension coefficient The two formulas are similar in form, but they are not the same?

Essentially, pressure = pressure * area, so tension = surface tension coefficient * area
Physical work formula
J = what, power = what
J is the unit function of Joule energy, w means w = FS, the direction of F and s should be consistent, w = (U & sup2 / R) * t or I & sup2; RT in electricity
Power P = w / T combined with the above formula, it is not difficult to find that P = FS / T = FV is about this
W=FS=Pt，P=FV=W/t
W (work) = Pt = FS = I * IRT unit J (joule)
P (power) = w / T = UI = FS / T = FV
Work = force x distance, i.e. w = FS
Power = work / time, i.e. P = w / T
p=w/t w=pt=uit
J is Joule, 1kW. H = 3.6 times the sixth power of 10 (power) P = w / T, the unit of power is Watt, the symbol is w,
Really depressed, who can tell me how to use the formula when doing physics problems, why I don't know what kind of formula to use when I see the problems
Because you don't know the formula, when you know it, you will
What are the physical research methods
Physics method is not only a method for scientists to study problems, but also a common method for students to learn physics. The new curriculum standard also requires students to master some physics methods to explore problems. The common physics method model method is to show abstract physical phenomena with simple and easy to understand concrete models. For example, using solar system model to represent atomic structure
What's the formula for, seconds and area
Be clear about case
The velocity is in small v,
Seconds are represented by lowercase s,
The area is shown in capital s
The distance is represented by a small s,
When learning physics, we should pay attention to the letter of physical quantity and unit
For example, the function is represented by the capital letter W, while the unit watt of power is represented by the small letter W
Speed: small V
Second: lowercase s
Area: capital S. how about the distance
What is the formula for calculating burn area?
Palm method: the wounded's five fingers are close together, and the palm area is about 1% of the body surface area. It is very convenient but not accurate for scattered small area burns (addition of burned skin) or large area burns (subtraction of healthy skin)
What's the formula for calculating area by lattice method?
For example, let the length between two points be 1, and each vertex of a closed graph is on a point. How to find the area of the graph?
Pick's formula: area of grid polygon = number of grids around the polygon △ 2 + number of grids inside the polygon-1
What is the formula of equal comparison substitution in physics?
First of all, the equivalent substitution method is a physical method, that is, a method for scientists to study problems
In the study of physical problems, sometimes in order to simplify the problem, one physical quantity is often used to replace all other physical quantities, but it will not change the physical effect. For example, the resultant force is used to replace each component force, the total resistance is used to replace each part of the resistance, and buoyancy is used to replace each pressure of liquid on the object
The second semester of the current people's Education Press
1. Area (M2): square s = A2 rectangle s = AB circle s = π (D / 2) 2
2. Volume (M3): cylinder v = sh drainage method v solid = v2-v1 cube v = A3 immersion V row = V immersion V row = V substance
3. Speed (M / s): definition v = s / T average speed v = s total / T total note: 1 m / S = 3.6 km / h
4. Definition formula of density (kg / m3) ρ = m / V floating object ρ = (V immersion / V object) · ρ liquid
Sinking object ρ = g object ρ liquid / (g object-g visual)
5. Gravity (n): g = mg, g = 9.8 N / kg ≈ n / kg
6. Buoyancy (n) formula method: F floating = ρ liquid GV row
Weighing method: F float = G-F bullet (f bullet is g sight) g sight represents the apparent weight of the object
Balance method: floating and floating: F floating = g matter
Archimedes principle: F floating = g row = m row G
Cause f floating = f upward - f downward when sinking to the bottom f floating = G-F branch
7. Pressure (PA): definition formula P = f / s liquid pressure: P = ρ liquid GH note: H is the depth under the free surface
8. Pressure (n): F = PS object on the water discharge plane f = g object
9. Work (Mechanical) (J): definition w = FS total work w total = w useful + W forehead note: 1 joule = 1 N · M
10. Power (Mechanical) (W): definition P = w / T = FV note: 1 watt = 1 J / S = 1 nm / S
11. Definition formula of mechanical efficiency: η = w useful / W total lifting weight: η = GH / Fs horizontal moving weight: η = FS / Fs
12. Lever balance condition (lever principle): f1l1 = f2l2 or F1 / F2 = L2 / L1, l is the arm of force
13. Resultant force (n): F in the same direction of the same line = F1 + F2, f in the opposite direction of the same line = f big - f small
14. Mechanical energy (J): mechanical energy = kinetic energy + potential energy
15. Heat (J): complete combustion of fuel: q = QM
Heat absorption and release: q = cm Δ t note: Δ t is the change of temperature
Endothermic formula: q = cm (t-t0) t is the final temperature, t0 is the initial temperature
Heat release formula: q = cm (t0-t) t is the final temperature, t0 is the initial temperature
16. Current (a): definition: I = q / T
Ohm's Law: I = u / R
Series circuit: the current is equal everywhere, that is: I = I1 = I2
Parallel circuit: the main current is equal to the sum of the branch currents, i.e. I = I1 + I2
17. Voltage (V): u = IR
Series circuit: the total voltage is equal to the sum of the voltages at both ends of each part of the series circuit, i.e. u = U1 + U2
Parallel circuit: the voltage at both ends of each branch is equal, that is: u = U1 = U2
18. Resistance (Ω): r = u / I note: conductor resistance only depends on conductor material, length, cross-sectional area and temperature, but has nothing to do with voltage and current
Series circuit: the total resistance of the series circuit is equal to the sum of the series resistances, that is, r = R1 + R2
Parallel circuit: the reciprocal of the total resistance of the parallel circuit is equal to the sum of the reciprocal of the parallel resistance, that is: 1 / r = 1 / R1 + 1 / r2 + 1 / R3
When two parallel connection: r = r1r2 / (R1 + R2)
When P and u are known: r = U2 / P
19. Electric power (W): definition P = w / T universal formula P = UI note: 1 volt ampere = 1 Watt
Derived formula P = U2 / R P = I2R note: it is only applicable to pure resistance circuit
20. Electric work (J): definition: w = uit
When the electric power is known: w = Pt note: 1 kwh = 3.6 × 106 joules
When the charge quantity is known: w = UQ
When the voltage resistance is known: P = U2 / R
When current resistance is known: P = I2R
21. Heat of conductor (J): Joule's law q = i2rt note: thermal effect of current
22. Electromagnetic wave velocity: C = λ f note: λ is the wavelength (m) f is the frequency (Hz) C = 3 × 108 M / S
1. Area (M2): square s = A2 rectangle s = AB circle s = π (D / 2) 2
2. Volume (M3): cylinder v = sh drainage method v solid = v2-v1 cube v = A3 immersion V row = V immersion V row = V substance
3. Speed (M / s): definition v = s / T average speed v = s total / T total note: 1 m / S = 3.6 km / h
4. Definition formula of density (kg / m3) ρ = m / V floating object ρ = (V immersion / V object) · ρ liquid
A sinking object... Unfolds
1. Area (M2): square s = A2 rectangle s = AB circle s = π (D / 2) 2
2. Volume (M3): cylinder v = sh drainage method v solid = v2-v1 cube v = A3 immersion V row = V immersion V row = V substance
3. Speed (M / s): definition v = s / T average speed v = s total / T total note: 1 m / S = 3.6 km / h
4. Definition formula of density (kg / m3) ρ = m / V floating object ρ = (V immersion / V object) · ρ liquid
Sinking object ρ = g object ρ liquid / (g object-g visual)
5. Gravity (n): g = mg, g = 9.8 N / kg ≈ n / kg
6. Buoyancy (n) formula method: F floating = ρ liquid GV row
Weighing method: F float = G-F bullet (f bullet is g sight) g sight represents the apparent weight of the object
Balance method: floating and floating: F floating = g matter
Archimedes principle: F floating = g row = m row G
Cause f floating = f upward - f downward when sinking to the bottom f floating = G-F branch
7. Pressure (PA): definition formula P = f / s liquid pressure: P = ρ liquid GH note: H is the depth under the free surface
8. Pressure (n): F = PS object on the water discharge plane f = g object
9. Work (Mechanical) (J): definition w = FS total work w total = w useful + W forehead note: 1 joule = 1 N · M
10. Power (Mechanical) (W): definition P = w / T = FV note: 1 watt = 1 J / S = 1 nm / S
11. Definition formula of mechanical efficiency: η = w useful / W total lifting weight: η = GH / Fs horizontal moving weight: η = FS / Fs
12. Lever balance condition (lever principle): f1l1 = f2l2 or F1 / F2 = L2 / L1, l is the arm of force
13. Resultant force (n): F in the same direction of the same line = F1 + F2, f in the opposite direction of the same line = f big - f small
14. Mechanical energy (J): mechanical energy = kinetic energy + potential energy
15. Heat (J): complete combustion of fuel: q = QM
Heat absorption and release: q = cm Δ t note: Δ t is the change of temperature
Endothermic formula: q = cm (t-t0) t is the final temperature, t0 is the initial temperature
Heat release formula: q = cm (t0-t) t is the final temperature, t0 is the initial temperature
16. Current (a): definition: I = q / T
Ohm's Law: I = u / R
Series circuit: the current is equal everywhere, that is: I = I1 = I2
Parallel circuit: the main current is equal to the sum of the branch currents. I = I1 + I2
17. Voltage (V): u = IR
Series circuit: the total voltage is equal to the sum of the voltages at both ends of each part of the series circuit, i.e. u = U1 + U2
Parallel circuit: the voltage at both ends of each branch is equal, that is: u = U1 = U2
18. Resistance (Ω): r = u / I note: the resistance of conductor only depends on the material, length, cross-sectional area and temperature of conductor, but has nothing to do with voltage and current.
Series circuit: the total resistance of the series circuit is equal to the sum of the series resistances, that is, r = R1 + R2
Parallel circuit: the reciprocal of the total resistance of the parallel circuit is equal to the sum of the reciprocal of the parallel resistance, that is: 1 / r = 1 / R1 + 1 / r2 + 1 / R3
When two parallel connection: r = r1r2 / (R1 + R2)
When P and u are known: r = U2 / P
19. Electric power (W): definition P = w / T universal formula P = UI note: 1 volt ampere = 1 Watt
Derived formula P = U2 / R P = I2R note: it is only applicable to pure resistance circuit
20. Electric work (J): definition: w = uit
When the electric power is known: w = Pt note: 1 kwh = 3.6 × 106 joules
When the charge quantity is known: w = UQ
When the voltage resistance is known: P = U2 / R
When current resistance is known: P = I2R
21. Heat of conductor (J): Joule's law q = i2rt note: thermal effect of current
22. Electromagnetic wave velocity: C = λ f note: λ is the wavelength (m) f is the frequency (Hz) C = 3 × 108 M / S
If you want more, qme: 506700379 put it away
Don't be too much ~ the main first 2
Ohm's Law: I = u / r u = IR r = u / I
Calculated electric energy: P = w / T
Measurement of electric power: P = UI = w / T = u ^ 2 / r = I ^ 2R
Joule's Law: q = I ^ 2rt [when q = w, q = w = Pt = uit = u ^ 2 / RT = I ^ 2rt]
Electromagnetic wave: C = λ f [C: wave speed, λ: wavelength, F: frequency]
Density formula: ρ = m / V
Buoyancy: F floating = ρ liquid GV row
Solid pressure: P = f / S
Liquid pressure: P = ρ GH
Ohm's Law: I = u / R
Density formula: ρ = m / V
Ohm's law of buoyancy: I = u / r u = IR r = u / I
Calculated electric energy: P = w / T
Measurement of electric power: P = UI = w / T = u ^ 2 / r = I ^ 2R
Joule's Law: q = I ^ 2rt [when q = w, q = w = Pt = uit = u ^ 2 / RT = I ^ 2rt]
Electromagnetic wave: Ohm's Law: I = u / R deformation formula obtained from experiment u = IR r = u / I (voltammetric resistance measurement)
Resistance series: r =... Expansion
Density formula: ρ = m / V
Ohm's law of buoyancy: I = u / r u = IR r = u / I
Calculated electric energy: P = w / T
Measurement of electric power: P = UI = w / T = u ^ 2 / r = I ^ 2R
Joule's Law: q = I ^ 2rt [when q = w, q = w = Pt = uit = u ^ 2 / RT = I ^ 2rt]
Electromagnetic wave: Ohm's Law: I = u / R deformation formula obtained from experiment u = IR r = u / I (voltammetric resistance measurement)
Resistance series: r = R1 + R2 parallel: 1 / r = 1 / R1 + 1 / R2 (r = r1r2 / R1 + R2)
Calculated electric power: P = w / T
Measurement of P: P = UI
P=U2/R
P=I2R
Joule's law q = i2rt (spring)

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