On the unit conversion of sand: 1 cubic meter =? Ton

On the unit conversion of sand: 1 cubic meter =? Ton

How many tons of sand per cubic meter

Sand 1 cubic meter is 1.1.7 tons, because the density of sand is 1400 ~ 1700kg / m3. Generally, fine sand is 1.4 tons (dry) per cubic meter, and coarse sand is 1.7 tons (dry)
If the sand is dry and wet, it can reach 35-40; if it is wet, it may be more than 50

If both sides of ∠ A and ∠ B are parallel, and ∠ A is 36 ° less than 3 times of ∠ B, then the degree of ∠ A is______ ．

The two sides of ∵ A and ∵ B are parallel respectively, and ∵ A and ∵ B are equal or complementary. There are two cases: ① when ∵ a + ∵ B = 180 °, the solution is: ∵ a = 3 ∵ B-36 °, and the solution is: ∵ a = 126 °; ② when ∵ a = ∵ B, ∵ a = 3 ∵ B-36 °, and the solution is: ∵ a = 18 °. So ∵ a = 18 ° or 126 °. So the answer is 18 ° or 126 °

X →∞, find the limit of (arctanx + SiNx) / 2x,
What is the limit of limx →∞, (arctanx + SiNx) / 2x,

Limit arctanx / 2x = 0 SiNx / 2x = 0
So the limit of the sum of the two is zero

There are three classes in Grade 6. The number of students in class 1 is 9 / 1 more than that in class 2. The number of students in class 2 is 6 / 1 less than that in class 3. The ratio of students in class 1 to class 2 should be calculated

The number of the second class is "1",
1 + 1 / 9 = 10 / 9
The number of three classes is: 1 △ 1-1 / 6 = 6 / 5
The ratio of the three classes is: 10 / 9:1:6 / 5 = 50:45:54

What is the answer to the number reasoning question: 0,2,3,0,8 ()?

0、2、3、0、8、（）
The beginning of the third term is equal to the square of the difference between the first two terms minus 1
（0-8)^2-1=63

The acceleration of an object with a mass of 1kg may be ()
A. 5 m/s2B. 7 m/s2C. 8 m/s2D. 9 m/s2

When two forces are combined, the range of resultant force is F1 + F2 ≥ f ≥ | F1-F2 | it can be seen that the range of resultant force of 3N and 4N forces is 7n ≥ f ≥ 1n. According to Newton's second law, the acceleration of an object a = f | m, it can be seen that the acceleration range of resultant force acting on 1kg object is 7m / S2 ≥ a ≥ 1m / S2, so AB is possible, CD is impossible

The first five terms of the sequence are the following numbers, write a general formula of each sequence: 1, 1,1 / 3,1 / 5,1 / 7,1 / 9; 2, - 1 / 2 * 1,1 / 2 * 2, -
The first five terms of the sequence are the following numbers. Write a general term formula for each sequence:
1、 1,1 / 3,1 / 5,1 / 7,1 / 9;
2、 - 1 / 2 * 1,1 / 2 * 2, - 1 / 2 * 3,1 / 2 * 4, - 1 / 2 * 5
3、 1,2 / radical 2,1 / 2, radical 2 / 4,1 / 4

1、 The numerator is 1 and the denominator is 2n - 1, so the general formula is an = 1 / (2n - 1)
2、 The numerator is 1, the denominator is n, and the front coefficient is (- 1) ^ n, so the general formula is an = (- 1) ^ n * 1 / n
3、 The latter term is √ 2 / 2 of the former term, so the general term formula is an = (√ 2 / 2) ^ (n-1)

The product of 2 / 3 and a number is exactly 3 / 5 of 20

Let this number be X
2/3*x=20*3/5
x=18
So the number is 18

The sum of two prime numbers is 39. The product of these two prime numbers is a natural number. The minimum multiple of a is 51. Its factor can be found

Because only one prime number is even, that's 2
39 is an odd number, which must be the sum of an even number and an odd number
Then it must be 39 = 2 + 37
So the product of these two prime numbers is 2 * 37 = 74
The minimum multiple of natural number a is 51
So a = 51
51=1*51=3*17
So its factors are 1, 3, 17, 51