A note on the calculation formula of physical quantities

Speed nu = s/t 1m/s = 3.6km/h sound speed nu nu = 340 m/s light speed c = 3×108 m/s.

Density ρ= m/V

The resultant force F = F 1-F2 (F 1 and F2 are on the same straight line and in opposite directions); F = F 1+F2 (F 1 and F2 are on the same straight line and in the same direction).

Pressure p = F/S p =ρg h p = F/S is suitable for solids, liquids and gases; P =ρg h is suitable for vertical solid columns; P =ρg h can directly calculate the liquid pressure 1 standard atmospheric pressure = 76 cmHg column =1.01×105pa =10.3m water column.

Buoyancy ① F float = g–f; ② Floating and suspending: f floating = G；; ; ③ F float = G row = g V row of ρ liquid; (4) judging buoyancy according to the ups and downs.

(1) Judge whether the object is subjected to buoyancy.

(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