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When a constant force is applied to an object in equilibrium, does the object accelerate? How does the acceleration change when the object changes from static state to motion? I think the object changes in an instant, because the applied force is constant, the acceleration becomes zero. How can we say that it is variable speed motion Is this sport really called variable speed sport?
Variable speed motion is called variable speed motion when the velocity (vector, with size and direction) changes (or size, or direction) (i.e., a ≠ 0), while variable speed motion is divided into uniform variable speed motion (constant acceleration) and variable acceleration motion (acceleration change)
A person throws an object vertically up at the speed V on the planet and falls back into the hands of human beings after time T. given that the radius of the planet is r, at least what speed can be used to launch the object along the surface of the planet so that the object does not fall back on the planet? （ ） A. 2vt R B. 2Rv T C. Rv T D. Rv 2T
The time for an object to go up and down is equal, both 1
2, then from the velocity formula, we can get:
v=gt
2；
The solution is: g = 2V
t；
On the surface of the planet
To keep an object from falling behind the planet, there are:
GMm
R2=mv2
R=mg=m2v
T
The solution is v=
2Rv
T
Therefore, B
People's education publishing house first volume of mathematics book all answers
You can find some reference books,
Many reference books have answers to exercises after class,
If you can't go to renjiao.com again,
Find the first volume of mathematics in junior high school,
Then look for e-books - teachers' books,
There should be an answer
Questions on page 19, Volume 1, grade 6 (people's Education Press) 8 Is Wang Ming's schoolbag overweight? Why?
I would like to add the topic: Children's weight should not exceed 3 / 20 of their weight. If they carry heavy objects for a long time, it will cause back pain and back pain, and even hinder bone growth. His schoolbag weighs 5kg, and the weight is 30kg. (1) is Wang Ming's schoolbag overweight? Why? Where are you from? I also read grade six!
Sorting out the knowledge points of mathematics textbook Volume 1 of Grade 7 of people's Education Press If the title ah, to the people's education press grade seven first four chapters of knowledge points, this is my most headache homework, I give you points
The knowledge points can be sorted out with the method of Catalogue: first, the table of contents before reading, sort out the general frame; second, turn each table of contents to the corresponding chapters in the book, and sort out the major titles, subheadings, and important formula theorems
If you want to make up the math well, do the examples in the book by yourself, think about it carefully, and then practice after the next book, so that the mathematics will be raised slowly~
How to do questions 4, 6, 7 and 8 on Page 38 in the first volume of the seventh grade mathematics book? (people's Education Press) 4. No more questions. Just 7 and 8 There are dividers and multipliers in the title, so there is no question I hope a kind-hearted person can also type out the process of solving the eighth problem
WOW! It's all calculation problems. You're too cruel. I'll tell you the answer
7,（1）24
（2）-210
（3）-3.2
（4）100
（5）-4/3
（6）-33/28
（7）0
（8）-11
8,（1）-243
（2）41.7
People's Education Press: six questions on 62 pages in the mathematics book of the sixth grade of primary school RT, how to do, online, etc., urgent!
There is no question 6 on page 62. Does it mean that the sea water and salt ratio is 100:3, so 585000 tons of sea water can be dried 585000 * 3 / 100 tons of salt, and 9 tons of salt needs 9 * 100 / 3 = 300 tons of seawater
People's education press senior one English compulsory 1 page 4
1 outdoors
2 upset
3 be concerned about
4 loose
5 go through
6 ignore
7 face to face
8 calm down
9 curtain
10 series
Who has a high school English compulsory 1, compulsory 2 word list ah, the English book is the people's education press
eureka
People's Education Press
This is an e-book for your class
It's all the words. Turn them page by page
However, it is quite comprehensive
come on.
Senior high school English compulsory 3 page 29 of the people's Education Press
1.What has not been discovered is his discovery.
2.Whether the other astronomers accept his ideas remains a question.
3.How life first appeared on earth is still a mystery to scientists.
4.Why the earth is becoming warmer is an important topic for research.
5.It amazed everybody that Stephen Hawking at 65 experienced zero gravity during a flight.
6.It is surprise that Pluto is no longer considered a planet in our solar system.
RELATED INFORMATIONS
- 1. People's education press, item 2 on page 5 of compulsory English for senior one
- 2. Help us 1.78 degrees - 47 degrees 34 minutes 45 seconds = 4.25 degrees = 3. If the sum of three consecutive odd numbers is 15, then the largest odd number is If 1 / 3 of a number is equal to this number minus 4, then this number is 5. If it is known that the price of a commodity after 20% reduction is 2800 yuan, the original price of the commodity is yuan 6. According to some statistical data, 664 cities in China can be divided into three categories according to water resources: temporary water shortage cities, general water shortage cities and severe water shortage cities. Among them, 50 cities are less than 4 times of the cities with serious water shortage, and 10 cities are generally short of water, which are twice as many as those with serious water shortage? 7. A group of businessmen gathered in the open-air teahouse. They had a table for two, and the waiter brought a bottle of juice to each table. Later, they changed to a table for three, and the waiter gave each table a bottle of wine. Soon, they changed to a table for four, At the end of the party, the waiter collected 50 empty bottles. If no one took away the bottles, how many people were there? 8. Someone was in an emergency and scheduled to take a small train from a to B. in fact, he took a minivan for a third of the way and then took a taxi, which doubled the speed and arrived an hour and a half ahead of schedule. The speed of the minivan is known to be 36 km / h, so the distance between the two places is required 9. Wang Liang made an appointment with his classmates to play table tennis at 4:30 p.m. each of them aligned his watch at 8:00 a.m. Wang Liang arrived on time at 4:30, but his classmates didn't come. The original classmate's watch was 4 minutes slower than the correct time. If the student arrived at 4:30 p.m., how much time would Wang Liang have to wait (the correct time)?
- 3. The little match girl
- 4. As shown in the figure, an object is thrown horizontally from point a on a slope with an inclination of 37 ° and the object falls on point B of the slope. The distance between two points AB and ab is measured to be 75m. Calculate the velocity of the object when it is thrown out and the velocity when it falls to point B
- 5. 8. The power formula P = fvcos α, the following understanding is correct (multiple choice) () A. It is derived from the definition of power P = w / T and the definition of work w = fscos α; B. If the angle between F and V α = 0, then p = FV; C. When V is the average speed and F is a constant force, then p = FV gives the average power; D. When f, V and α are instantaneous values, P = fvcos α gives instantaneous power
- 6. The answer to the final question of 508-08 "brand of electric bicycle in Guangdong Province is as follows Battery Specification: 36 V 12 ah (battery) vehicle mass: 40 kg Rated speed: 210 R / min (RPM) Dimension: l 1800 mm × w 650 mm × h 1100 mm, charging time: 8 h Motor: rear wheel drive, DC permanent magnet motor rated working voltage / current: 36 V / 5 A According to the relevant data in the name plate, the rated speed of the vehicle is about A.15 km / h b.18 km / h c.25 km / h d.30 km / h
- 7. An object of mass m glides along a rough slope at a constant speed_____ In addition to gravity, the resultant force of other external forces is equal to_____ , the direction is_______ .
- 8. As shown in the figure, the object is in equilibrium under the action of five common forces. If the force F1 is removed and the remaining four forces remain unchanged, please draw the magnitude and direction of the resultant forces of the four forces on the diagram
- 9. Using known angle in cosine theorem to find area In a triangle, if the angle a is 60 degrees, then the area s is? (expressed by a, B, c)
- 10. The sum of two acute angles of a right triangle is greater than the sum of two acute angles of an obtuse triangle, right
- 11. Some problems about inverse function of function A common function such as y = SiNx can be expressed as f (x) = SiNx, y (x) = SiNx. What are the expressions of F (y), y (x) and F ~ - 1 (x)?
- 12. What is the inverse function of F (x) = (x + 1) inx-x + 1?
- 13. Why do we need to find the range of the original function when we find the inverse function of a function
- 14. Let x satisfy inequality 2 (Log1) 2x)2+7log1 2X + 3 ≤ 0, find the function f (x) = (log2x) 4)(log2x 2) Maximum and minimum values of
- 15. Given that x satisfies 8 ≤ x ≤ 32, find the maximum and minimum values of the function f (x) = log2x / 8 · (log2x-1)
- 16. Given that the inverse function g (x) of the function f (x) = 2x satisfies g (a) g (b) = 4, find the minimum value of 1 part of a and 1 part of B
- 17. 0
- 18. What is the coordinates of the intersection point between the image of the inverse function of F (x) = log3 (x + 3) and the Y axis?
- 19. It is known that the function y = f (x) has the value of inverse function in its definition domain (- ∞, 1), f (x) = x ^ 2-2x, f ^ - 1 (- 1 / 2)
- 20. It is proved that the inverse function of the function y = (1-x) / (1 + x) (x is not equal to - 1) is the function itself