In English

In English

Distance [S] = speed [v] × time [t]

How to understand the formula of distance and time

The formula: v = s / T, right
It is the relationship between the time t used to walk a certain distance s, and the time used to walk a unit of distance is the speed
v=s/t

Speed × time = distance?
If speed doesn't directly say a value in the question, is it a constant or a variable?

Speed × time = distance
For this formula, speed refers to the average speed. When the time and distance are determined, the speed can be calculated, which is a constant. If the time and distance are only known, the speed cannot be directly calculated, which is a variable

Time is fixed. What's the ratio between distance and speed

If the speed and distance change,
When the time is fixed, the distance is proportional to the speed

The driving time is fixed, and the driving distance is proportional to the speed______ Proportion

Driving distance: speed = time (certain), is the corresponding ratio, so the driving distance and speed are in direct proportion; so the answer is: positive

The length of the lower railway bridge of Nanjing Yangtze River Bridge is 6772m, of which the main river bridge is 1577m long. It takes 2min for a 200m long train to pass through the main river bridge. What is the speed of the train? What is the time to pass the whole railway bridge?

Train speed v = s / T = (1577 + 200) / (2 * 60) = 14.8m/s
It takes t = s / v = (6772 + 200) / 14.8 = 471 seconds to completely pass the whole railway bridge

Conversion formula of physical time in grade two of junior high school

Time progression rate: 60 s = 1 min, 60 min = 1 h, 1 h = 1 D, 365 d = 1 a (year), 1 m / S = 3.6 km / h

What are the physical formulas of grade two

Physical quantity (unit) formula velocity V (M / s) v = s: distance / T: time gravity g (n) g = mg m: mass G: 9.8n/kg or 10N / kg density ρ (kg / m3) ρ = m / V M: mass V: Volume resultant force F (n) same direction: F = F1 + F2 opposite direction: F = F1-F2 opposite direction

All the formulas, their variations, and the quantities represented by the letters

Unit formula of physical quantity
Name symbol name symbol
Mass m kg m = ρ V
Temperature T ° C
Velocity v m / S M / S v = s / T
Density ρ kg / M 3 kg / M 3 ρ = m / V
Kg / M 3 kg / m3
Force (gravity) f Newton (cow) n g = mg
Pressure P Pascal PA P = f / S
Work w Joule (joule) J W = FS
Power P watt W P = w / T
Current I a (a) a i = u / R
Voltage U V U = IR
Resistance R ohm (Ω) r = u / I
Electric work w Joule (joule) J W = uit
Electric power P watt (watt) W P = w / T = UI
Heat Q Joule J Q = cm (t-t0)
Specific heat C coke / (kg · C) J / (kg · C)
The speed of light in vacuum is 3 × 108 M / s
G 9.8 N / kg
Sound speed 340m / s in air at 15 ° C
The safety voltage is not higher than 36 v
1, liquid pressure P = GH; 2, Archimedes principle f floating = g discharge = Liquid GV discharge; 3, lever balance
Conditions: f1l1 = f2l2; 4. Mechanical efficiency = × 100%; 5. Joule's Law: q = I2 r t
(if the circuit is pure resistance circuit, then: q = w); 6. If you know the rated voltage and rated voltage of an electrical appliance
If the power p value and the actual voltage U value, then the resistance R = P value = () 2p value when the appliance works normally
7. Power P = FV; 8. Characteristics of series circuit: I = I1 = I2; u = U1 + U2; r = R1 + R2;
Characteristics of parallel circuit: I = I1 + I2; U1 = U2 = u
power
M row: the mass of liquid in row
ρ liquid: density of liquid
V row: volume of liquid to be discharged
(volume immersed in liquid)
Balance condition of lever f1l1 = f2l2 F1: power L1: power arm
F2: resistance L2: resistance arm
Fixed pulley f = g
S = H F: 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 an object rises
Moving pulley f = (g object + G wheel)
S = 2 h g object: the gravity of the object
Wheel G: gravity of moving pulley
Pulley block f = (g object + G wheel)
S = N H N: the number of segments of the rope passing through the movable pulley
Mechanical work W
(J) W = FS F: force
s: The distance moved in the direction of the force
Useful work
Total work w total w = g matter H
Wtotal = FS, when the pulley block is placed vertically
Mechanical efficiency η = × 100%
Power p
（w） P=
W: Merit
t: Time
Pressure P
（Pa） P=
F: Pressure
S: Stress area
Liquid pressure P
(PA) P = ρ GH ρ: density of liquid
h: Depth (from liquid level to desired point)
The vertical distance of the
Heat Q
(J) Q = cm △ T C: specific heat capacity m: mass
Δ T: change value of temperature
Fuel emission
Q (J) q = MQ M: mass
q: Calorific value

Some formulas of physics in the second grade of junior high school
Buoyancy calculation formula
Ask for all
Pressure calculation formula
Atmospheric pressure calculation formula
Calculation formula of liquid pressure

The formula of buoyancy: F = g row
be-all:
Pressure formula: P = f / S
Atmospheric pressure formula: 1. The standard atmospheric pressure is 1.01 * 1000000pa
The formula of liquid pressure: P = P liquid GH