Come and solve this problem, you have the ability to advance

Haha and where pi=

Don't bother me to prove that these two numbers are irrational.

What's the matter, I'm familiar with these two irrational numbers, how dare you do it.

The root of the second is five plus three.

Subtract. The root of the second is number five.

One is because Xiaoqiang is at least 17 meters away from Shanggu, so he hears an echo.

What is the release of the introduction, is it the release of earthworms?

The first question is echo, which is the sound of sound waves reflecting off the valley. The second question is a vacation?

The first is: echoing or seeing cockroaches.

The second. Ignorance.

I don't understand the second question, the first question is an echo.

The first one is an echo, and the second one can't be understood!~

Since r=U2P, the resistance of 30W is twice that of 60W. So the voltage on a 30W bulb is 220*2 3, and the voltage on a 60W bulb is 220 3

Let u=220V

For 30W bulbs: U2 30 = U2 * (4 9) P, P = 40 3 W

For 60W bulbs: U2 60 = U2 * (1 9) P, P = 20 3 W

The total power is 40 3 + 20 3 = 20W

The team will answer for you.

Analysis: 1. From the formula r u 2 p forehead, the resistance of the two bulbs can be obtained r30 220 2 30 respectivelyr60＝220^2/60

In a circuit connected in series at 220V, their total power is:

Total U 2 (R30 R60) 220 2 (220 2 30 220 2 60) 20 (W).

2. The respective power P30 and P60 can be obtained by the following methods:

From the formula p30 p60 p, we get: p30 p60 20 ......①

From the formula p30:p60 r30:r60, we get p30:p60 (220 2 30):(220 2 60), i.e. p30:p60 2:1......②

Solve and form a system of equations to obtain p30 40 3 (w), p60 p = 20 3 (w).

You're talking about the big picture.

In fact, the way to do big questions is nothing more than that you have to learn the knowledge of the first year of high school and the second year of high school I believe you also know that most of the big questions of physics in the college entrance examination are the combination of electromagnetism, magnetism and force and the combination of circular motion.

There is also to do more big questions like the college entrance examination Don't you know how to improve if you do more?

Hehe, give it the best.

Oh, the problem of physics, especially the big question, as far as my personal experience is concerned, is actually a synthesis of many physical processes, distinguish the basic principles of each physical process and the formulas to be used, note, you must figure out the principle, and then according to the principle you understand the equations, which must not guess the physical process, no matter how big the problem is actually the superposition of the simple process, you can split it into a few small problems to do, I hope these are useful to you Of course, the foundation is the key issue.

Do more questions.

Listen carefully in class.

Eat the textbook thoroughly.

Relax, don't get too nervous on it.

Junior high?

Isn't a resemblance coming out?。。

There is a problem with the question, AB does not mean that BC does not constitute a parallelogram.

Solution: Let the two cities of AB be X kilometers apart.

It depends on the topic.

Solution: x=2844 (km) Thank you.

Solution: First find the time of two cars and two encounters, and regard the distance between the two cities as the unit "1", then the speed of car A is 1 8, the speed of car B is 1 10, and the time of the two cars meeting is 1 (1 8 1 10) 40 9 hours.

When the car is 158 kilometers away from the midpoint, it means that car A exceeds the midpoint by 158 kilometers, and car A goes 158*2 kilometers more than the express train.

So the distance between the two cars is: 158*2 [(1 8 1 10)*40 9] 2844 km.

The second method:

If the distance between the two cities is x kilometers, then there is.

x 2 158 x 10 * [x (x 8+x 10)] solution x 2844 km.

Assuming a distance of x, then A is x 8 km per hour and B is x 10 per hour.

Relative departure, the time used to meet is x (x 8+x 10) time multiplied by the speed of B x (x 8+x 10)]*x 10), the distance travelled, x 2 - [x (x 8+x 10)]*x 10)=158

I am also a junior high school student, the teacher taught us to start with the conclusion he asked to prove, if he asked to prove the relationship between the sum and difference between the two line segments, then the pants resistance auxiliary line must be extended or intercepted, if the two line segments are required to be equal, then the most common is to prove that the two triangles are congruent, and there is no triangle to construct a triangle. Or use the conversion method. Occasionally, it needs to be proven in proportion.

For example, a b = c b then a = c if you can master these methods, you will basically be fine. In fact, I was also confused, but with the increase in the number of questions, I will be able to make perfect, I wish you progress in your studies.

There are too few questions, just do more exercises.

There are no shortcuts, just practice. Rubber scrambler.

Summarize the rules when doing the questions, for example: when you see the right angle and the midpoint, you should think of the connection; Liang Wendan sees the key point and thinks of connection.