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Three-year junior high school mathematics physics and chemistry subjects related formulas
1, the speed formula of uniform linear motion:

Find the speed: v=s/t

Find the distance: s=vt

Discovery time: t=s/v

2. the speed formula of variable-speed linear motion: v = s/t.

3. The relationship between the weight and mass of an object: G=mg (g=9.8N/kg).

4. Definition of density

Find the density of matter: ρ = m/v.

Find the mass of matter: m = ρ v.

Find the volume of matter: V=m/ρ

4. Pressure calculation.

Definition: p=F/S (substances can be used in any state)

Liquid pressure: p=ρgh(h is depth)

Find the pressure: F=pS

Find the stress area: s = f/p.

5. Calculation of buoyancy

Weighing method: f floating = g-f

Formula: F float =G row = ρ row V row G

Float method: F float =G object (V row < V object).

Suspension method: F float =G object (V row =V object)

6. Lever balance condition: F 1L 1=F2L2.

7. definition of work: W=Fs

8. power definition: P=W/t

For uniform linear motion: P=Fv (F is a power)

9. Mechanical efficiency: η = useful power/total power

For lifting objects:

W useful =Gh(h is height)

W total =Fs

10, slope formula: FL=Gh.

1 1, heat absorption and heat release when the temperature of the object changes

Q suction = cm Δ t (Δ t = t-t0)

Q amplifier = cm δ t (δ t = t0-t)

12. Calculation of heat released by fuel combustion: Q =qm.

13, heat balance equation: q absorption =Q discharge.

14, heat engine efficiency: η=W useful /Q amplifier (q amplifier =qm)

15, current definition: I=Q/t (Q is electric quantity in coulomb).

16, ohm's law: I=U/R

Deformation voltage: U=IR

Deformation resistance: r = u/i.

17. Features of series circuit: (Take two pure resistance appliances in series as an example)

Voltage relation: U=U 1+U2

Relationship of current: I=I 1=I2.

Resistance relation: R=R 1+R2.

18. Features of parallel circuit: (Take two pure resistance appliances in parallel as an example)

Voltage relation: U=U 1=U2.

Relationship of current: I=I 1+I2.

Resistance relation:1/r =1/r1+1/R2.

19, electric work calculation: W=UIt.

20. the definition of electricity is p = w/t: p = w/t.

Common formula: P=UI

2 1, Joule's law: Q amplifier =I2Rt

For pure resistance circuit: Q amplifier = I2RT = U2T/R = UIT = Pt = UQ = W.

22. Calculation of total power of lighting circuit: P = P 1+P 1+ ...