How to define volume flow and mass flow? How to convert?

How to define volume flow and mass flow? How to convert?

Mass flow the amount of fluid mass flowing through a cross section per unit time
Volume flow the volume of fluid passing through the flow section in unit time, referred to as flow, expressed by Q
1m3/h=1t/h=0.28l/s

Given the volume flow of gas under standard condition, how to convert the volume flow under working condition according to working temperature and working pressure?
What is the formula for conversion?

I think we should use this formula: PV= NRT.NR It is a constant. The volume changes with the change of pressure and temperature
So V2 = v 1, T 2, P / T 2, P 2. In this way, I think we can get the flow formula

Calculation of gas flow with known pressure, temperature, volume and time
In a container, first vacuum, and then fill it with air, there are timing, temperature measurement and pressure measurement in the container, to calculate the flow when filling

Using equation of state of ideal gas
PV = NRT, where p is the pressure, V is the volume of the container, n is the mole number of air, R is the general gas constant, and t is the absolute temperature of the gas
According to P, V, R (known constants), t, n can be obtained
M = nm, where m is the mass of gas entering the container, n is the number of moles, and M is the molar mass of air
In this way, we can find out the mass of air entering the container
QM = m / T, where QM is the mass flow symbol, M is the gas mass and t is the time
From this, we can calculate the air mass entering the container in unit time, that is mass flow

If the product of two matrices is a zero matrix, what is the relationship between the ranks of the two matrices?

I almost forgot. I only remember one:
If the product of two n-order matrices is a zero matrix, then the sum of the ranks of the two n-order matrices is less than or equal to n

Class 51 went boating in the park. Originally, they planned to rent several boats. If one boat was added, there would be six people on each boat; if one boat was reduced, there would be six people on each boat
It happens that there are 9 people on each ship. How many people are there in class 51? How many ships were originally planned to charter?

6(x+1)=9(x-1)
-3x=-15
X = 5 6 * 6 = 36 A: there are 36 people in total, and the original rent is 5

Limx → π / 2 (LN (SiNx)) / (π - 2x) ^ 2

lim(x→π/2) (ln(sinx))/(π-2x)^2 (0/0)
=lim(x→π/2) cotx/[-4(π-2x)] (0/0)
=lim(x→π/2) -(cscx)^2/8
=-1/8

The odd function f (x) whose domain is r satisfies f (x) = f (x-2k) (K ∈ z), and when x ∈ (0,1), f (x) = 2 ^ X / 4 ^ x + 1
1. Find the analytic expression of F (x) on [- 1,1]
2. Prove that f (x) is a decreasing function on (0,1)
3. When m takes what value, the equation f (x) = m has a solution on (0,1)?

When 1 x ∈ (0,1), f (x) = 2 ^ X / 4 ^ x + 1 = 2 ^ (- x) + 1, let t = - x, then, - t ∈ (0,1), so f (- t) = 2 ^ t + 1, and f (x) is an odd function, so f (- t) = - f (T), so f (- t) = - f (T) = 2 ^ t + 1, so f (T) = - 2 ^ T-1, so the analytic expression of F (x) on (- 1,0) is f (x) = - 2 ^ X-1, and the analytic expression of F (x) on (0,1) is f (x) = 2 ^ (- x) + 1
It's not necessary to prove that it's a decreasing function. It's OK to calculate the derivative
3, f (x) - M = 2 ^ (- x) + 1-m has a solution, 2 ^ (- x) = M-1 has a solution, so 1 / (m-1) = 2 ^ (x), if we want to make the equation have a solution, then

Wait for me, I'm coming?

wait for me,I am coming.

Exercises on the absolute value of rational numbers by multiplication and division

It's contained by a calculation problem_ O ha!
|﹣2/3|÷﹙2/3－4/5﹚＋|4/9|
I'm a little annoyed. Count carefully!

Calculation: (1 / 100-1) x (1 / 99-1) x (1 / 98-1) x... X (1 / 2-1)

（1/100-1)x(1/99-1)x(1/98-1)x...x(1/2-1)
.=（1-100/100)x(1-99/99)x(1-98/98)x...x(1-2/2)
=（-99/100)x(-98/99)x(-97/98)x...x(-1/2)
=-（99/100)x(98/99)x(97/98)x...x(1/2)
=-1/100