The physical meaning of period and speed

The physical meaning of period and speed

The linear velocity of a circle is equivalent to that of a straight line. The formula is v = L / T, l is the arc length, t is the time. The difference between the linear velocity of a circle and that of a straight line is that the direction of the linear velocity of a circle is constantly changing, and the one-way direction of a straight line does not change. The angular velocity is the angle of rotation in a certain period of time
If the volume of a ball is four times that of the radical three, what is the surface area?
0,
V=(4π/3)R^3=4√3π,
Then R ^ 3 = 3 √ 3 = (√ 3) ^ 3
∴R=√3.
Then its surface area is SS = 4 π · R ^ 2 = 12 π
Two thirds of the 12 factions.
It should be right.. It's been a long time.
30 practical problems in Mathematics in the second semester of grade five
1. There is a total of 6400 meters in a canal. In the first three months, the average monthly repair is 1200 meters. The rest needs to be completed in two months. How many meters should be completed on average?
2. Mr. Wang and Mr. Li bought the same books. Mr. Wang spent 256 yuan to buy 8 books, and Mr. Li spent 192 yuan. How many more books did Mr. Wang buy than Mr. Li?
3. The farm tool factory originally planned to produce 400 pieces of farm tools per month. After the technological innovation, the production in nine months exceeded the annual plan of 780 pieces. Now how many pieces are produced per month on average?
4. There are 50 baskets of apples, 2 baskets less than twice the number of pears. How many baskets are there in all?
5. A batch of cloth was originally planned to make 1800 sets of clothes. As each set saved 0.2 meters of cloth, 100 more sets were made. Now how many meters of cloth are used for each set?
6. Party A and Party B work together to process a batch of parts and complete the task in 20 days. It is known that Party A makes three more parts per day than Party B, and Party B asks for five days' leave in the middle of the process. Therefore, the number of parts completed by Party B is exactly half of that of Party A. how many are the total number of these parts?
7. A machine factory plans to complete 10800 machine tools in 30 days. Due to the improvement of technology, 180 more machine tools will be manufactured every day than the original plan. In this way, the task can be completed several days in advance?
8. There are two bags of rice. The weight of a bag of rice is 1.2 times that of B bag. If 5 kg is added to B bag, the two bags of rice will be the same?
9. A barrel of oil weighs 45 kg, and after half of it is poured out, there is 23 kg left. If this kind of oil costs 4.5 yuan per kilogram, how much can it cost per barrel?
10. Each bag of wheat is 60kg, and each bag of rice is 90kg,
Only know the total weight of wheat, the total weight of rice more than 1800 kg
How many bags?
11. If you pour 20% out of a barrel of gasoline, it's exactly 24 kg. How many kg does this barrel of gasoline weigh
12. A clothing factory produced 4500 sets of sportswear in February, 10% less than that in January. How many sets of sportswear were produced in January?
13. In a 10 hectare wheat field, the average wheat yield is 4.8 tons per hectare. Based on the flour yield of 85%, how many tons of flour can be ground?
14. The four walls of Mingming's room need to be painted. The room is 4 meters long, 3 meters wide and 3 meters high. Except the area of doors and windows is 4.7 square meters, 0.6 liters of paint is used for each square meter, and a barrel of lipang dream thousand color exterior wall sub gloss paint is 4.5 liters, 286 yuan per barrel. How much yuan does it cost to paint Mingming's room?
15. What's the percentage of boys in the class? What's the percentage of boys in the class?
16. A 30 meter long steel pipe is sawed into three sections. The first section is 7 meters long, 2.5 meters shorter than the second section. How long is the third section?
17. There is a swimming pool, which is 25 meters long, 12 meters wide and 1.4 meters deep. There are 2 decimeter long square white tiles on the bottom and around the pool. How many pieces do you need?
18. An engineering team builds a 15.8km long highway. In the first week, it builds 5km. In the second week, it builds 0.7km more than in the first week. How many kilometers will it take to finish?
19. There is 2100 cubic meters of water in the cuboid reservoir, which is 50 meters long and 20 meters wide. How many meters deep is it?
20. The school transported 7.6 cubic meters of sand and soil. How thick can it be paved in a sand pit 5 meters long and 3.8 meters wide?
21. A water conservancy project team builds an average of 125 meters of canals every day in the first four days and 134 meters every day in the last three days. How many meters of canals does the project team build every day?
How long is the square iron frame of 22 cm at least?
23. Make an iron box with iron sheet so that its length, width and height are 1.8 decimeters, 1.5 decimeters and 1.2 decimeters respectively. How many square meters of iron sheet should be used to make such an iron box?
24. Our school needs to paint the classroom. The classroom is 8 meters long, 7 meters wide and 3.5 meters high. After deducting the area of doors, windows and blackboard by 13.8 square meters, it is known that it costs 5 yuan per square meter for painting. How much does it cost to paint a classroom?
25. The length, width and height of the drawers are 2.8 decimeters, 1.5 decimeters and 2.2 decimeters respectively. How many square meters of wood should be used to make five such drawers?
26. The processing factory needs to process a batch of TV sets (without bottom). Each TV set is 60cm long, 50cm wide and 55cm high. How many square meters of cloth should be used to make 1000 sets?
27. There is a kind of cuboid steel, which is 2 meters long. Its cross section is a square with a side length of 5 cm. Each cubic decimeter of steel weighs 7.8 kg. How many kg does this square steel weigh?
28. A cuboid swimming pool is 60 meters long, 30 meters wide and 2 meters deep. How many square meters does the swimming pool cover? Draw a water line with red paint at 1.5 meters along the inner wall of the swimming pool. What's the length of this line? Now the water in the swimming pool just reaches the water line, so how about the volume of the water in the pool?
There are 23 boys and 25 girls in grade 29 and grade 5. What percentage of boys are girls? What percentage of the class are boys and girls?
30. The number of qualified students in class 3 of grade 5 of Shengli primary school is 24, and the number of unqualified students is 12. What is the proportion of qualified students in the whole class?
31. The machine tool plant completed 1 / 6, 1 / 5, 4 / 15 and 7 / 10 of the tasks of the whole year in the four quarters of last year, respectively. What percentage of the annual plan was overfulfilled last year?
32. Go into life. Class 5 students of grade 5 perform in line. There are 12 or 16 people in each line. It is known that there are less than 50 students in this class. Can you work out how many people there are in this class?
Mr. Li took 67 yuan and bought 6 sets of story fairs, 9 yuan each. How many yuan are left.
1、 Addition and subtraction of fractions
1. The fifth grade students participate in extracurricular group, the number of students participating in science and technology group accounts for the total number of students in the whole grade, the number of students participating in literature and art group accounts for the total number of students. What is the total number of the two groups in the whole grade?
2. A vegetable field, it's eggplant, pepper, the rest of the cucumber. How many parts of the land is Cucumber Planted?
3. Divide six apples of the same size to eight children on average, and each child gets a big piece and a small piece. How is it divided? How much is it for each child?
2、 Multiply fraction by
1、 Addition and subtraction of fractions
1. The fifth grade students participate in extracurricular group, the number of students participating in science and technology group accounts for the total number of students in the whole grade, the number of students participating in literature and art group accounts for the total number of students. What is the total number of the two groups in the whole grade?
2. A vegetable field, it's eggplant, pepper, the rest of the cucumber. How many parts of the land for cucumbers?
3. Divide six apples of the same size to eight children on average, and each child gets a big piece and a small piece. How is it divided? How much is it for each child?
2、 Fractional multiplication
4. The side length of a square is meters. How many meters is its perimeter?
5. One kind of soybean contains about kilogram of oil per kilogram. How many kilogram does 100 kilogram soybean contain? What about a ton of soybeans?
6. Shengli road is 1 km long, and Yan'an road is twice as long as Shengli road. How many kilometers is Yan'an road longer than Shengli road?
7. The area of a rectangular desktop is 1 square meter. A square table top with a side length of meters. How much more is the area of a rectangular desktop than that of a square desktop?
8. 195 machine tools will be assembled in a factory. Six of them are not installed in 33 days. How many units are installed per day? (solution of a series of equations)
9. There are two baskets of apples. The first basket weighs 30 kg. If one kilogram is taken out of the first basket and put into the second basket, the two baskets are equal in weight. How many kilos do two baskets of apples weigh
10. An object weighing 1kg on the earth weighs only 1kg on the moon. A classmate weighs 36kg. If he goes to the moon, how many kg lighter is his weight than on the earth?
11. There are 44 students in class one of grade five. The number of students who participate in the chorus team accounts for the total number of students in the class. How many people participate in the chorus team?
12. A duck weighs 3 kg, and a chicken weighs duck. How many kg does this chicken weigh?
13. A volleyball is priced at 60 yuan. The price of basketball is volleyball. How much is the price of basketball?
14. The road construction team plans to build 4 kilometers of roads. It has already built them. How many kilometers have they built?
15. A whale is 7 meters long, and its head is 30 meters long. How many kilometers is the head of this whale?
16. The total length of Chengdu Kunming railway is 1100 km, with bridges and tunnels accounting for about 50% of the total length. How many kilometers are the bridges and tunnels?
17. A rectangular piece of land is 24 meters long and long in width. How many square meters is the area of this piece of land?
18. The incubation period of goose is 30 days, that of duck is goose, that of chicken is duck. How many days is the incubation period of chicken?
3、 Fractional division
19. The little owner's chicken has 8 eggs in a day, and the total weight is kg. How many kg does each egg weigh on average?
20. The perimeter of a square is meters. How many meters are its sides?
4、 Four mixed operations and application problems of fraction
21. In order to celebrate the school anniversary, class three of five years has to make 180 small flags, which have been made. How many more have not been made?
22. The original price of a garment is 105 yuan. Now the price is reduced. How much is the current price?
23. The students took part in the brick transportation work, and transported 1500 pieces in two days. On the first day, how much did you get on the second day?
There are 30 books on science and technology, and 18 books on science and technology, accounting for 30% of this batch of books. How many of these new books are there?
5、 Cuboid and cube
24. Lixin farm tools factory needs to build a brick wall of 15m long, 24cm thick and 3M high. If 525 bricks are used per cubic meter, how many bricks will be used?
25. A knapsack sprayer. The volume of the liquid chest is 14 litres. If you spray 700 ml of liquid medicine every minute, how many minutes does it take to finish spraying a box of liquid medicine?
Revision
Score application questions
26. (1) a road was built in a certain township. It was 2 kilometers in the first day, and more in the second day than in the first day. How many kilometers were repaired the next day?
27. (1) grade five students need to paste a batch of cartons, a total of 600. It was done by the first shift alone and completed in 3 hours; it was done by the second shift alone and completed in 4 hours. Now it's done by two classes. How many hours can it be completed?
28. There are 20 baskets of apples, totaling 540kg. If there are more apples in each basket, how many kilograms of apples can each basket hold?
29. Party A and Party B make a batch of children's clothes together. It takes 10 days for factory a to do it alone, and it takes 5 more days for factory B to do it alone than factory a. How many days can the two factories work together?
30. For a batch of parts, it takes 15 hours for Party A to do it alone and 12 hours for Party B to do it alone. If two people work together for 3 hours, and the rest is finished by B, how many hours will it take? Put it away
City god horse
The relationship between rotational speed and angular velocity, f (frequency) in Physics
Rotational speed n -- the number of revolutions in 1 min
Frequency f -- revolution of 1s
f=n/60
Angular velocity W -- the number of radians (RAD) of rotation angle
W = 2 / F = 2 / N / 60
A straight prism with equilateral triangle at the bottom, each edge of which is 10 cm long, its surface area and volume (accurate to 0.1)
S bottom = 10cm * 10cm = 100cm2
S side = 10cm * 10cm * 3 = 300cm2
S table = 100 + 300 = 400cm square
Volume: s base = 100cm square
Bottom * height = its volume = 100 * 10 = 1000cm3
S is wrong. It should be better 10 * 5