How to solve additional problems in Math and Physics

You need to grasp 70% of the basic questions in mathematics, and you will do the additional questions after you have a good grasp of the previous questions. Mathematics additional questions are actually the comprehensive use of knowledge, to make use of all the mathematical knowledge you have learned, geometry questions to see the requirements of the question and then look at the diagram, and then as an auxiliary line.

Physical buoyancy remember the formula f float = density of liquid multiplied by volume of discharge multiplied by g

In fact, many students have such a misunderstanding, always think that only by buying a lot of information books, and then finishing, can you have a good grade, in fact, otherwise, as long as you learn all the most basic knowledge on the book (I am talking about all), because books need experts for many years to compile, and a printing company can compile many copies a year, if you are not at ease, just buy a relatively simple information book and put it in your heart, hehe, as long as you are serious about everything can learn very well, No topic can be separated from the knowledge of textbooks!

Mathematics: Find out the knowledge points and see if they need to be used as auxiliary lines, or to prove congruence, or to rotate.

Physics: Memorize the buoyancy formula, find the corresponding data, and bring in the evaluation.

Before the exam, you should review the scope of the case, and then find some questions to practice your skills, and the exam will be in the order from easy to difficult.

Buoyancy needs to be clear about the difference between the liquid surface and the liquid surface, especially the buoyancy is equal to the gravity of the liquid.

Practice math on your own.

The title of this question is:"Relative motion between blocks occurs only when the acceleration a1 of the block is greater than the acceleration of the plank a2"

In this case, a1=(f1-umg) m a2=umg m=1, it can be concluded that f1>5 will only occur relative motion between them.

So there is no relative motion between them at f=, so the time it takes for the plank to advance is the time for the whole system to advance.

Let the acceleration of the system be a3, a3=f (m+m)=*, so t=2 seconds.

Shopping 1-199 yuan, not preferential, the money paid is the actual value of the purchased goods 130 yuan in the range of 1-199 yuan, so the actual value of the purchased goods is 130 yuan.

For purchases over 400, 400x90% + over 400 x 80% = 360 + over 400 x 80%.

It can be seen that the money paid is more than 360 yuan.

So 380 yuan is in this file, and the part that exceeds 400 pays 380-360 = 20 yuan, so the actual value of the part over 400 is 20 80% = 25 yuan The total actual value: 400 + 25 = 425 yuan.

Didn't save money the first time.

The second time saved: 425-380 = 45 yuan.

So he saved a total of $45.

6 Bah! Acceleration a=v2-v1, basic concept.

You give me the formula for accelerating motion.