Impinging air jets may be used to clean particles from surfaces. The kinetic energy per unit volume (J/m3) of an air jet at a surface, Er, may be written as:
E=1/2*(rho*v2)* k*d-1.3
Where:
rho = density of air (1.3 kg/m3),
v = air velocity
k = proportionality constant (0.4 mm 1.3)
d = distance from the jet nozzle (10 mm).
For a sphere (A4 = 1x10-19 J) adhered to a flat surface (A2 = 1x10-20 J), find:
1. What size of particle (diameter) could a hurricane force wind (v = 118 km/h) remove from a
surface?
2. What size of particle can be removed at v = 340 m/s (speed of sound)?
3. What air velocity would be required to remove a 1 mm particle and a 100 nm particle?

i think they are all correct

explanation:

they seem good

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.