The expression of instantaneous velocity

The expression of instantaneous velocity

Let v be the instantaneous velocity in the middle. According to the displacement formula, we can get (V ^ 2-V ^ 2) / 2A = (VT ^ 2-V ^ 2) / 2a, so V ^ 2 = (VT ^ 2-V ^ 2) / 2A

Junior high school stage on the electromagnetic wave formula, to indicate what is the description of physical quantities, letters, units, concise~
Also, what's the relationship between V and C in the formula? What does it mean? Sorry, it's a bit confusing here=

C = λ F, indicating wave speed, wavelength and frequency respectively; the unit is m / s, m and Hz respectively
C is the wave velocity

Use the measured physical quantity (letter) to write the expression of iron ore density
(Huangshi City, 2007) a student of a school visited a mine in Daye. He saw a technician weigh a small piece of iron ore in air and immersed in water (the density is ρ water) with a spring dynamometer, and then compare the following table to determine the price of iron ore
Ore density (g / cm3) 3.23.43.63.84.04.2
Iron content (%) 17 22 27 32 38 44
Price (yuan / T) 75 100 L25 150 200 260
(3) Use the measured physical quantity (letter) to write the expression of iron ore density ρ=________ .
The answer is the density of water * g / (G-F). Why?

G-F is actually the buoyancy of the ore when it is immersed in water. The density of (G-F) / water is the volume of the ore. g divided by volume = density. The density of water is above the semicolon because it is divided twice

Speed limit sign table instantaneous speed or average speed?

Instantaneous. As long as it exceeds the speed limit, it will be considered as overspeed. If it is average, it is allowed to accelerate sharply and slow down after exceeding the limit, but in fact, it is not allowed