What do junior high school physics formulas stand for?

The speed of sound nu = 340m/s.

The speed of light c = 3× 108 m/s.

Density ρ = m/v1g/cm3 =103kg/m3.

Resultant force F=F 1-F2

F=F 1+F2F 1, and F2 is on the same straight line with opposite directions.

F 1 and F2 are on the same straight line and in the same direction.

Pressure p = ft/s

P=ρghp=F/S is suitable for solids, liquids and gases.

P=ρgh is suitable for vertical solid columns.

P=ρgh can directly calculate the liquid pressure.

1 standard atmospheric pressure =76cmHg column =1.01×105pa =10.3m water column.

Buoyancy ①F float = g–f

② Floating and suspending: f floating = g.

③F float =G row = gV row of ρ liquid.

(4) Judging the buoyancy According to the fluctuation (1), it is judged whether the object is buoyed.

(2) According to the ups and downs of the object, judge what state the object is in.

(3) Find a suitable formula to calculate buoyancy.

Conditions for the ups and downs of an object (premise: the object is immersed in liquid and only subjected to buoyancy and gravity):

①F float > g (ρ liquid > ρ substance) floats to float ②F float =G(ρ liquid = ρ substance) suspends.

③F float < g (ρ liquid