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It took 50 seconds for a train to cross a 1230 meter long bridge and 70 seconds to cross a 1830 meter long tunnel at the same speed To solve the equation Find the length again
Let the train speed be x m / s. 50x-1230 = 70x-1830, x = 30
Or (1830-1230) / (70-50) = 30 (M / s)
What is the maximum length of a straight line?
China's Highway Line Design Code stipulates that the maximum length of highway straight line shall not exceed 20V (m)
If the design speed is 120km / h, the maximum length of the straight line
It is: 20 * 120 = 2400m
What is the minimum length of straight lines between curves in the same direction
When the design speed is greater than or equal to 60 km / h, the minimum length of straight line between curves in the same direction (in M) should not be less than 6 times of the design speed (in km / h); when the terrain conditions and other special conditions limit, the minimum length of straight line should not be less than 3 times of the design speed (in km / h)
In the particle of ro3n -, there are x electrons outside the nucleus. If the mass number of R atom is a, then the number of neutrons in the R nucleus is 1 mol. there are mol protons in the particle
It's mainly the latter question, which has an answer but is not sure,
Let R be the number of protons in R nucleus
The number of electrons outside the nucleus of R atom is also r
According to the meaning of the title: R + 8 * 3 + n = X
r=X-24-n
Then the number of neutrons in R nucleus is A-R = a - (x-24-n) = A-X + 24 + n
The number of protons in the particle is (x-24-n + 8 * 3) mol = (x-n) mol
What is filled subgrade? What is cut subgrade? (low embankment - what is the meaning of slope height in filled subgrade with slope height less than 1m?)
The simple description is: Fill Subgrade: the subgrade section whose design elevation is higher than the ground elevation. Cut subgrade: the subgrade section whose design elevation is lower than the original ground elevation. The slope height described here: the slope top design elevation minus the slope toe elevation is the slope height
The number of particles of any particle in 1mol
I don't know the formula n = n / Na very well. Can you explain it in detail?
N refers to the "amount of matter" of a specific substance, the unit is mol. and N is the total number of particles contained in the substance (this number is very large). Na is the amount of particles contained in each mol substance, which is called "Avogadro constant". Symbol: Na, its value is 6.02 × 10 ^ 23. Every mol substance contains so many particles! This point
As for the design drawing of basic farmland consolidation, how to calculate the irregular area? How to calculate the earthwork volume of filling and excavation?
1. Using planimeter is a kind of instrument for area calculation; 2. Using drawing tool Cass (CAD) to calculate area; 3. Drawing on checkerboard and checking the number of occupied cells, calculate them in proportion; 4. Dividing irregular area into small similar regular areas and calculating them separately. The first two kinds of area calculation are fast. Fill and cut: according to the datum line you give
The mass of 1mol oxygen is 32g / mol, right?
Why?
No, the unit is wrong
The molar mass of oxygen is 32 g / mol
The mass of 1mol oxygen is 32g
What is the difference between tread width and section width?
Looking at the picture I sent, the section refers to the distance between the two sidewalls after cutting off the tire, and the tread refers to the part contacting the ground
What factors affect the volume of 1mol substance
Because the volume of a substance is affected by the external environment (the above two factors), in order to facilitate the study, we have formulated a standard state: the so-called standard state is the state of the substance under the specified temperature T and standard pressure P, referred to as the standard state
RELATED INFORMATIONS
- 1. How many kilometers is it from one place to another? Is it the straight-line distance between the two places or the length of the highway route?
- 2. An engineering team built a 1200 meter long highway, which took 8 days to build 4 / 15 of the total length. According to this calculation, how many days will it take to complete the highway
- 3. An engineering team has built a highway, which is 1200 meters long. At this time, the ratio of the length of the highway to that of the highway is 3:10, What's the length of this highway?
- 4. An engineering team built a 1200 meter long highway, which took 8 days to build 4 / 15 of the total length. According to this calculation, how many days will it take to complete the highway
- 5. There are 100 tons of clean water tanks in the waterworks. Three water pipes of the same size are used to deliver water at the same time. After t hours, the water is discharged, Each pipe is known to drain x tons per hour 1. Write the functional relationship between T and X 3. When t = 10, calculate the value of X
- 6. Taian Wuyue Special Purpose Vehicle Co., Ltd. is a large-scale production base of special purpose vehicle. In the vehicle type test, a special purpose vehicle of this factory runs 5.6km on a straight road evenly, and the resistance is 30000N, which consumes fuel
- 7. In the model test of a special vehicle of junior high school physics, it drove at a constant speed of 80km / h for 6km on a straight road, consuming 1.5L of fuel, In the model test, a special purpose vehicle runs at a constant speed of 80km / h on a straight road for 6km. The fuel consumption is 1.5L. It is known that the density of gasoline is 0.7 * 10 cubic kg / M cubic, and the calorific value of gasoline is 4.5 * 10 seventh power J / kg. Assuming that the fuel is completely burned and the efficiency of gasoline engine is 40%, how much resistance does the vehicle receive in the process of driving at this speed
- 8. It is known that a domestic car consumes 8 liters of gasoline for every 100 km. What is the mass of gasoline consumed by the car for 100 km
- 9. The fuel consumption of a car is 10L for every 100km. Given that the density of 93 oil used by the car is 0.75 × 103kg / m3, the fuel consumption of the car for 100km is 0.75 × 103kg / m3
- 10. After driving at a constant speed of 72 km / h for 10 minutes, a car consumes 1.2 kg of gasoline, half of which is converted into traction and recharges the battery The electric energy stored in the battery increases by 7.2 × 10 ^ 6J. How much resistance does the car suffer? (the calorific value of gasoline q = 4.6 × 10 ^ 7J / kg, and Q discharge = QM)
- 11. It took 50 seconds for the train to cross a 1140 meter long bridge and 80 seconds for the train to cross a 1980 meter long tunnel
- 12. A road team built a road, 186 meters in total in the first six days. At this speed, it took nine days to finish. How long is the road? To use the solution proportion solution, list the relationship, such as X * y = K
- 13. After six days of building a highway, it is more than 120 meters above the midpoint, and the rest will continue to be built at the original speed. It can be completed in five days. How long is the highway?
- 14. A highway subgrade is 100km long and 50m wide. How many square kilometers and hectares does the highway subgrade cover? No wrong number
- 15. The subgrade of a highway is 100 kilometers long and 50 meters wide. How many hectares and square kilometers does the subgrade cover
- 16. In our country, the maximum speed limit is 120km / h. someone is supposed to drive along the straight road at the highest speed, The acceleration of the car when braking is 5m / S2, and the driver's reaction time (from the time when he realizes to stop to operate the brake) is 0.6-0.7s?
- 17. How to calculate the area of highway subgrade cross section? For example: 3.10m subgrade width left: 10.75 right: 10.75 slope 1:1, what's the excavation area
- 18. (2 / 2) m, width of road
- 19. What is the appropriate width of sidewalks for all levels of urban roads
- 20. What's the width of the zebra crossing? What's the width of the road section? Thank you?