The main unit of the main principle of physical quantities

Length (L) (1) Measure (2) the distance moved in the direction of force (3) with a ruler: s= (4) arm of force = (5) the depth of liquid.

(6) the thickness of the object h= a=

Kilometers, meters, decimeters, centimeters, millimeters, etc.

1 km =1000m

1m= 100cm

Area (s) (1) area formula S = AB S = A2 S = π R2 = π D2.

(2) Volume formula (3) Pressure formula

1 m2 = 102 m2

1dm2= 102cm2

1cm2= 102mm2

Volume (V) (1) Mathematical formula V positive =a3 V length =Sh=abh V column = =Sh V ball = π R3 (2) Density formula (3) V = V2-V 1 (4) V = V row = F floating/ρ liquid G is partially exposed when submerged by Archimedes principle.

1dm3= 103cm3

1cm3= 103mm3

Time (t) (1) Definition of speed (2) Power (3) Measured by clocks.

1h = 60 minutes

1 min = 60 seconds

Speed ()

( 1) (2)

1 m/s = 3.6 km/h

Mass (m) (1) Gravity formula (2) Work formula

(3) Measure the density with a balance formula (4).

1t= 1000kg

1 kg =1000g

1 g = 1000 mg

Density (ρ) (1) has (2) pressure formula (3) Archimedes principle F floating = ρ liquid gV discharged and then ρ liquid =

1 g/cm3 = 1000

Kg/m3

The resultant force (f) (1) in the same direction f = f 1+F2 (2) in the opposite direction f = f1-F2 (f1> F2) n.

Pressure (p) (1) (applicable to all solids and liquids) (2) Applicable to all liquids and solids (cuboids, cubes and cylinders) whose sides are perpendicular to the bottom (1pa = 1n/m2).

Buoyancy (F float) (1) Weighing method F float = G-F means (2) Pressure difference method F float = F up -F down.

(3) Archimedes principle method F floating = ρ liquid gV row (4) floating or floating method F floating = g.

Strength and resistance

Just be the same as the unit.

Work (w) (1) definition W=Fs gravity work W=Gh=mgh friction work W=fs.

(2) Total work W =F total moving s W = w usage +w quantity.

Useful work = ghw has = w total-w amount

(3)η= W Yes =ηW Total w Total = (4) W=Pt

1J= 1N.m

= 1w.s

Mechanical efficiency (η) (1) η = =

(2) η= =

(3) For pulley block η= (n is the number of strands on the moving pulley)

(4) η= =

Since useful work is always less than total work, η is always less than 1.

When the pulling force (f) (1) does not include the weight and friction of the moving pulley and rope, f = (2) does not include the weight and friction of the rope, (3) generally uses (n is the number of rope strands on the moving pulley) (4) the object moves at a uniform speed, generally f = F= (2 f is generally friction).

Power (P) (1) P = (2) P = = (3) read from the nameplate of the machine.

1w= 1J/s

= 1 nm/sec

Specific heat (c) (1) q absorption = cm (t-t0) q discharge = cm (t0-t) can be unified as q = cm △ t.

rule

(2) q amplifier = QM (q is J/kg m, unit is kg)

(3) q amplifier = qv (q is m3 to J/ m3 V)

(4)Q- absorption = Q- emission without heat loss (heat balance equation)

The unit of c is

J/(Kg。 The specific heat capacity of water is 4.2× 103J/(Kg. The physical meaning is 1kg. The heat absorbed by water is 4.2× 103J.

The charge amount (Q) (1) is defined as Q = IT (2) W = UIT = UQ, and Q = (Q is the charge amount).

The unit of q is C.

Definition of current (I) (1) (Q is the amount of charge) (2)

(3) w = uite rule

(4) P = UI, then (P is electric power)

(5) Joule's law Q = I2RT is

(6) If the pure resistance circuit w = UIT = I2RT, then

(7) p = ui = i2r, then

(8) series connection: I = i 1 = I2 parallel connection: I = i 1+I2 (9) read from the ammeter 1A = 1000ma.

Voltage (U) (1) (Q is the amount of charge) (2) U = IR (3) (4)

(5) Joule's Law (Q is the heat generated) Then (6) Series connection: U = U 1+U2 Parallel connection: U = U 1 = U2.

(7) Read 1 kV = 1000 V from the voltmeter,

1V= 1000mV. The household circuit is 220V, and the safe voltage to human body is not more than 36 V.

Resistance (R) (1) (principle of measuring resistance by voltammetry) (2) W = UIT = I2RT =

(3)

(4) Joule's Law Q = I2RT (Q is the heat generated)

(5) Series connection: r = r 1+r2, then r 1 = r-r2r2 = r-r 1.

(6) Parallel connection: (7) Read the words "10Ω1a" on the sliding rheostat from the ohmmeter or nameplate. 1ω= 1V/A

1mω= 106ω

1kω= 103ω

Electric work (w) (1) w = UIT = uq (q is the amount of charge) (2) w = q =

(3) P = W = (4) W = Q = when there is no heat loss.

(5) Read out from the electric energy meter (unit: Kwh). The international unit is J, and the commonly used unit on electric energy meters is kW.h.

1KW.h=3.6× 106J

Power (P) (1) (2) P = (3) read from electrical appliances.

1Kw= 1000w

1 HP = =735w W。

When electric heating (q) (1) does not calculate heat loss, q = w =

(2) heat balance equation q absorption = q let its unit be j.

Electrification time (t) (1) (Q is the amount of charge) (2) w = UIT, then

(3) p = then (4) q = then

You'd better give me your qq mailbox so that I can send you the documents.