What is the relationship between density and mass Don't copy it on the Internet

What is the relationship between density and mass Don't copy it on the Internet

Density is a physical quantity reflecting the characteristics of matter. The characteristics of matter refer to a kind of nature that matter itself has and can distinguish from each other. People often feel that the matter with high density is "heavy", while the matter with low density is "light". Here "heavy" and "light" essentially refer to the size of density
Mass is the amount of material contained in an object. If the material contained is reduced, the mass will be reduced. Density is a property of a material. It does not change with the change of mass and volume. The density of the same material does not change
Density is a property of matter. It is only related to the kind of matter, but has nothing to do with mass, volume and other factors
The formula of density: (ρ is density, M is mass, V is volume)
ρ=m/v

A square plus b square equals 1, a times b equals - 4, find the value of a, B

It is known that all parabolic ellipses pass through the point m (1,2), and they have the same focus on the x-axis Find the standard equation of parabola

(1) If the point m is in the first quadrant and the focus of the parabola is on the x-axis, then let the parabola be y & # 178; = 2px (P > 0)
If P = 2, then y & # 178; = 4x
(2) Y & # 178; = 4x, the focus is (1,0), the ellipse focus is F1 (1,0), C = 1, F2 (- 1,0)
∵|MF1|+|MF2|=2a=√[(1-1)²+(2-0)²]+√[(1+1)²+(2-0)²]=2+2√2
∴a=1+√2
∴b²=a²-c²=3+2√2-1=2+2√2
The elliptic equation is X & # 178; / (3 + 2 √ 2) + Y & # 178; / (2 + 2 √ 2) = 1

How to calculate the pressure and stress area of cylinder?
For example: how can a 50 * 100 cylinder calculate its pressure and stress area

(square of cylinder inner diameter x3.14 - square of piston rod diameter x3.14) x air pressure = theoretical output of cylinder
Pay attention to the unit

Formal multiplication formula method
The laws are as follows: (1) 1 × 2 × 3 × 4 + 1 = 25; 2 × 3 × 4 × 5 + 1 = 121; 3 × 4 × 5 × 6 + 1 = 361; 4 × 5 × 6 × 7 + 1 = 441
(2) According to the above results, Chen Cheng thinks: the sum of the product of four natural numbers and 1 must be a perfect square number. Why?

Let the minimum number be X
x(x+1)(x+2)(x+3)+1
={x(x+3)}{(x+1)(x+2)}+1
=(x^2+3x)(x^2+3x+2)+1
=(x^2+3x)^2+2(x^2+3x)+1
=(x^2+3x+1)^2
therefore
A number which is 1 larger than the product of four continuous natural numbers must be a complete square number

The general solution of the total differential equation (3x ^ 2 + 6xy ^ 2) DX + (6x ^ 2Y + 4Y ^ 2) dy = 0

（3X²+6xy²)dx+(6x²y+4y²)dy=0 3X²dx+4y²dy+(6xy²dx+6x²ydy)=0dx³+4dy³/3+3dx²y²=0 x³+(4y³/3)+3x²y²=C

How many tons is a cubic meter of steam?

Under the standard condition, 18 / 22.4 = 0.80357 g / L saturated steam temperature density pressure reference table temperature (℃) density (kg / m3) absolute pressure (MPA) 100 0.61.103 101 0.611 1.05 102 0.639 1.088 103 0.66 1.127 104 0.6

Several multiplication formula questions!
1.(3a+b)^-（3a-b)^
2.79.8^
3. Solving equation: (x-1) (X-2) + (X-2) (x + 2) = 2 (x-3) (x + 3) - 2
4. First simplify, then evaluate
(1) . y (x + y) + (x + y) (X-Y) - x ^, where x = - 2, y = half
(2) . x + y ^ = 50, x + y = 10
PS: ^ is the square! I hope the answer is clear!

1. (3a + b) ^ - (3a-b) ^ = (3a + B + 3a-b) (3a + B-3A + b) = 6A * 2B = 12ab2.79.8 ^ = (80-0.2) ^ = 6400-32 + 0.04 = 6368.04 3. Solve the equation: (x-1) (X-2) + (X-2) (x + 2) = 2 (x-3) (x + 3) - 2 (X-2) (2x + 1) = 2x ^ 2-18-22x ^ 2-3x-2 = 2x ^ 2-18-23x = 18x = 64

Calculate triple integral, subscript integral area is Ω, find ∫ ∫ Z ^ 3dxdydz, Ω is x ^ 2 + y ^ 2 + Z ^ 2 ≤ 1, Z + 1 ≥ x ^ 2 + y ^ 2 under root sign

The original formula = ∫ D θ∫ RDR ∫ Z & # 179; DZ (for cylindrical coordinate transformation)
=(2π)(1/4)∫[(√(1-r²))^4-(r-1)^4]rdr
=(π/2)∫(4r^4-8r³+4r²)dr
=(π/2)[(4/5)r^5-2r^4+(4/3)r³]│
=(π/2)(4/5-2+4/3)
=(π/2)(2/15)
=π/15.

How many meters is 70 kilometers?

One kilometer is 1000 meters, 70 kilometers is 70000 meters