Ask the master to help you answer, and ask the great god to answer

On a recent day, at breakfast, I peeled a hard-boiled egg and placed it vertically on the mouth of a glass bottle, and a small half of the egg was submerged in the bottle. I used to press the egg with my fingers, but when I pressed it into the bottle, it shattered into several pieces. At this time, I suddenly thought:

Is it possible to put this bare egg in a bottle without damaging it? I posed this question to my dad, who thought for a moment and said, "It should be fine."

Dad took out a few pieces of waste paper and crumpled them together, lit them with a match, and carefully threw them into the bottle. My dad said to me, "Look, I'm going to do magic!"

He put a shelled egg on the mouth of the bottle, pressed it lightly with his hand, and only heard a "pop", and the egg fell into the bottle completely.

I was surprised, "What's the trick here?" Dad said, "I'll do a little experiment, and you'll understand." ”

Dad put a candle on a small dish, then put it in a basin of water, let the candle protrude about a third of the way out of the water, light the candle, and then cover the candle with a glass bottle; Put a few more supports on the mouth of the bottle to hold the bottle up a little, so that water can enter and exit the bottle; A mark is also made on the outer wall of the bottle that is flush with the surface of the water. The candle burns for a while and then goes out. At this time, I noticed that the water in the bottle had risen to one-fifth of the hollow part of the bottle.

How so? Dad told me that when the candle burns, the oxygen in the bottle is used up, and the oxygen is only about one-fifth of the air.

When the oxygen laughing gas is used up, the flame is extinguished, and the water is pushed into the bottle by the air pressure outside. In the experiment of pushing eggs into the bottle, because the shelled egg seals the entire bottleneck, the outside air cannot enter the bottle to replace the consumed oxygen, so the air pressure in the bottle decreases, and the egg is sucked into the bottle.

I really didn't expect that as long as you pay attention to everything, everything and everywhere in life, there will be many new discoveries!

The electronic frog eye is designed based on the frog's eye (sensitive to moving things).

The title is not clear, and the following is a bit of a bluff guess, if there is a mistake, it is because the title is not clear.

22.known points a(2,-3),b(-1,2); c(6，-4)，d(-3，1)；Find the coordinates of the vector ab+cd.

Solution: 23A linear equation that crosses the point (3,-1) and is parallel to the linear vector v(1,2).

Solution: The linear equation is: (x-3) 1=(y+1) 2;

24。The straight line 3x+4y-25=0 is separated from the garden x +y=4, and the maximum and minimum distances from the point on the garden to the straight line are obtained.

Solution: The radius of the garden = 2; The distance from the center of the circle (0,0) to the straight line 3x+4x-25=0 h= -25 (9+16)=25 5=5;

The maximum distance from the point on the old garden to the straight line = 5 + 2 = 7; Minimum distance = 5-2 = 3;

24.The equation for the garden through a(0,0),b(5,-3),c(1,1).

Solution: The equation for setting up a garden is (x-a) +y-b) =r ;

Substituting the coordinates of the above three points at one time obtains:

a²+b²=r²..5-a)²+3-b)²=r²..1-a)²+1-b)²=r²..

Replace , and substitute , simplifying: -10a+6b+34=0....

Replace , and substitute , simplifying it as: a+b-1=0....

10 gets: 16b+24=0, so b=-24 16=-3 2;Substituting the formula to obtain a=1-b=1+3 2=5 2;

Then substituting the values of a and b into the equation is: r = 25 4 + 9 4 = 34 4 = 17 2;

The standard equation for the old garden is: (x-5 2) +y+3 2) =17 2

Or write as: x -5x+y +3y=0

a=456 b=123

b+a is to concatenate the strings of b and a, and the result is"123456"

What, I don't know about this.

3. How many copies of "Nature's Secrets" were purchased.

How many copies of the small encyclopedia were purchased.

How many books the school has purchased.

How many more copies of "Nature's Secrets" than "Little Encyclopedia".

s=a*al=(a+b)*2

a*m c/a c/ms/t s/v v*t

How many bottles of mineral water are there?

How many bottles of drinks are there.

How many bottles of drinks and mineral water are there?

How many more bottles of mineral water than drinks.