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Is it possible for an object to speed to the right and accelerate to the left? Please give an example to illustrate ~ ~ urgent! Wait online ~ ~ thank you Questions on page 26 of high school physics exercise book~~~
Of course, there are many examples. Car braking is the most common example. Acceleration has direction and speed also has direction. In addition, you block and push the oncoming cart in the opposite direction. The speed of the car is towards you, but it's deceleration. At this time, you give the car a force opposite to the speed, so
As shown in the figure, when the car accelerates to the right, the block m is stationary on the vertical wall of the car relative to the car. When the car's acceleration increases ()
A. M's static friction increases, B. M's pressure on the car wall increases, C. m may fall onto the car, D. M's static friction remains unchanged
A. according to Newton's second law, the friction force F = mg remains unchanged. So a is wrong and D is correct. When the acceleration of B and C cars increases, the elastic force n = ma increases, and the maximum static friction force on the block increases. The block cannot slide along the wall. So B is correct and C is wrong. So BD is selected
When the car starts from a standstill, that is, the acceleration a is uniformly accelerated, then the speed of the car ()
A. At the same time, the maximum value B. has not reached the maximum value C. has reached the maximum value d before reaching the rated power. After that, the speed will remain unchanged
When the car just reaches the rated power, it also has acceleration, from f-f = ma and P = FV, then f gradually decreases, acceleration a also gradually decreases, and the speed continues to increase, until the acceleration is zero, the speed reaches the maximum, so ACD is wrong, B is correct. So select B
x^2-9y^2-x-3y
With the help of those who have done wrong
x^2-9y^2-x-3y=(x+3y)(x-3y)-(x+3y)=(x+3y)(x-3y-1)
The square of (x + 2) - 5x + 6 = 12
Using formula method
The square of (x + 2) - 5x + 6 = 12
x² +4x+4 -5x +6 -12 = 0
x² -x -2 = 0
(x-2) (x+1) = 0
X = 2 or - 1
In terms of formula
quadratic formula
X = 1 ± root (1 + 8) / 2
=( 1 ±3) / 2
=2 or - 1
Given the square of a + B-2 + (AB + 3) = 0, find the value of 2 [AB + (- 3a)] - 3 (2B AB)
Requirements: ensure the correctness, accuracy and integrity of the process
If one is greater than 0, the other is less than 0
So both are equal to zero
So a + B-2 = 0, AB + 3 = 0
a+b=2,ab=-3
Original formula = 2ab-6a-6b + 3AB
=5ab-6(a+b)
=5×(-3)-6×2
=-15-12
=-27
5x-39 = 56 solution test
5x-39=56
5x-39+39=56+39
5x=95
5x÷5=95÷5
x=19
24x+180-32x=102
24x+180-32x=102
180-102=32x-24x
8x=78
x=39/4
Solve the following equation (1) 2 / 7 times (X-7) = 2 minus 2x / 3
3
How to turn off the scientific calculator for students
There are two ways. If there is an ellipse in the middle, press shift first, then AC, and if there is no ellipse, press off directly
RELATED INFORMATIONS
- 1. The trolley moves in a straight line with uniform acceleration to the right, and the block m sticks to the left wall of the trolley, and is relatively static with the left wall. When the acceleration of the trolley increases, the following statement is correct 1. The friction force on the block remains unchanged; 2. The elastic force on the block remains unchanged; 3. The friction force on the block increases; 4. The external force on the block increases
- 2. In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform variable speed linear motion, the following listed% 2 In order to reduce the relative error of measuring the acceleration of the trolley in the experiment of measuring the acceleration of the uniform linear motion, which of the following measures are beneficial? A. Make the acceleration of the car as small as possible B. Appropriately increase the number of hook codes hanging under the string C. Under the same conditions, make multiple tapes and choose one of the most ideal ones for measurement and calculation D. Round off the dense points on the paper tape, and then select the counting points for calculation Mainly B option, our teacher said to reduce the number of hook code, why
- 3. Static friction and dynamic friction When the thrust is greater than the maximum static friction, the object is pushed, Then the force can be reduced slightly Doesn't the thrust have to be less than the maximum static friction? If it's less than, it's still This becomes: thrust is greater than the maximum static friction, impossible. Thrust is less than the maximum static friction, static. Then how does it move
- 4. What does the formula of sliding friction mean?
- 5. What is the formula for maximum static friction and sliding friction?
- 6. How to calculate rolling friction?
- 7. If the solution of the linear equation of one variable - KX = k is x = - 1, the following condition must be satisfied?
- 8. The solution of the linear equation KX = 6 with one variable of X is an integer. Find the value of the integer K Who is going to teach you the answers to the seventh grade mathematics in the experimental version of the top students' class hour paper?
- 9. As shown in the figure, if the line y = KX + B passes through two points a (3,1) and B (6,0), then the solution set of the inequality system 0 < KX + B < 13X is______ ．
- 10. If the absolute value of 3-2k of (K-2) x + 2K = 4 is a one variable linear equation of X, then k =? As soon as possible, as soon as possible
- 11. Which of the following situations are possible? Please explain according to examples. (1) the speed of the object is very large, and the acceleration is very small. (2) the speed of the object is equal to 0, and the acceleration is not equal to 0. (3) the speed of the object is constant, and the acceleration is not equal to 0
- 12. The direction of static friction on an object may be perpendicular to the direction of motion of the object. Who can explain? It's best to give an example
- 13. Does static friction do work or not depends on the selected reference frame?
- 14. In the formula of sliding friction f = μ n, can μ be greater than 1?
- 15. As shown in the picture, a and B measure the distance from the river bank to the cliff. Standing on the bank, a is 20m away from B. they stand on a straight line from the river bank to the cliff. A fires a shot, B hears two shots, and the interval between the two shots is 4S. Calculate the distance from the river bank to the cliff. (set the sound propagation speed as 340 & nbsp; m / s)
- 16. How to calculate the work done by an object on an inclined plane? What is the formula?
- 17. How many forces does an object bear when it is placed on an inclined plane? I wrote about gravity, support force and static friction force. I want to ask if I wrote more or less
- 18. How to measure static friction and sliding and rolling friction? Calculation formula So under what circumstances is the force acting on an object equal to static friction?
- 19. Static friction and sliding friction Isn't the maximum static friction the horizontal thrust of an object at the moment when it is about to move? Then the friction becomes smaller when the object gets up? Besides, doesn't sliding friction require the object to move relatively? If the thrust of the object is less than sliding friction, how does it move, A thing weighs 500N, the maximum static friction is 300N, and u is 0.56. One asks how much force is given to keep it moving at a constant speed when it moves, and how much sliding friction is given to push it 200N until it stops? The answers are all 280n. What's the matter? 200N is smaller than 280n. How does it move?
- 20. How to calculate the area of a circle