What does this story make us understand

What does this story make us understand

Do not just talk, but act

Can you give a living example to illustrate the practical significance of the inequality 2x + 5 > 11?

The two brothers had the same amount of money. They wanted to buy a bunch of carnations for their mother, but the money was still not enough. So they borrowed 5 yuan from other students. This time, it was enough. Then they had at least how much money each had

Can you give a living example to illustrate the practical significance of the inequality 2x + 5 > 11?

The two brothers had the same amount of money. They wanted to buy a bunch of carnations for their mother, but the money was still not enough. So they borrowed 5 yuan from other students. This time, it was enough. Then they had at least how much money each had

The two ends of the rope with length of L = 5m are respectively tied to the top a and B of the two poles with a distance of 4m on the ground. A 12n object with a smooth hook is hung on the rope to calculate the tension of the rope
Why right angles?

The two ends of the rope with length of L = 5m are respectively tied to the top a and B of the two poles with distance of 4m on the ground. A 12n object with smooth hook is hung on the rope, and the tension (10N) of the rope is drawn. Finally, a right triangle is formed. The tension side length is 2.5m, the gravity side length is 1.5m, so the gravity / tension = 1.5 * 2

Physical problems (composition and decomposition of forces)
A small ball with a mass of 0.1kg in the aircraft is connected with a spring with negligible mass and stiffness coefficient of 12.5n/m. The ball is placed on a smooth horizontal plate Mn. When the aircraft taxis along the Mn direction on the horizontal runway at a constant speed until the spring is stable, the spring is compressed by 4cm

According to f = FX and F = ma
Acceleration a = FX / M = 12.5 * 0.04 / 0.1 = 5m every second
The plane sped up five meters per second

As shown in the figure, a ball with radius R and weight g is hung on a vertical smooth wall by a string with length R. if the angle between the string and the wall is 30 degrees, the tension t of the string and the elastic force n of the wall are ()
A. T=G，N＝G2B. T=2G，N=GC. T＝3G，N＝32GD. T＝233G，N＝33G

According to the synthesis method, the resultant force of the rope tension and the wall elastic force is inversed to the equivalent gravity. Using the geometric relationship, t = GCOS 30 ° = 233g, n = gtan 30 ° = 33g. Therefore, D is correct and a, B and C are wrong. Therefore, D is selected

Decomposition of physical forces
Who can give me a clear explanation of the decomposition of force (including the situation that the magnitude and direction of two components of a force are partially determined)
Note, if the answer is good, I may give you a certain reward
Note: Please attach relevant figures when analyzing and explaining.

1. Know the direction of the resultant force and two components, and solve the two components. Use parallelogram. 2. Know the direction of the resultant force and one component, and solve the maximum value of the second component

The maximum tensile force that a light string can bear is g. now put a heavy g object system at the middle point of the rope, hold the two ends of the rope together, and then slowly separate them symmetrically. If you want the rope to be continuous, the angle between the two ropes should not exceed ()
A. 45°B. 60°C. 120°D. 135°

The force analysis is shown in the figure: the resultant force of the two forces is always g, and the angle is gradually increasing, so the two forces gradually increase, and the tension F of the rope on both sides reaches the maximum value of G, then the sum of the components of the forces on both sides in the vertical direction is equal to the gravity g, and the solution is: 2gcos (θ 2) = g, and the solution is: θ = 120 ° so select: C

How to find the equal angle in the decomposition of the force, after the decomposition of the force, we don't know which is longer and which is shorter, and how to judge which angle corresponds to the angle

If you don't know the angle, remember that the x-axis is sin and the y-axis is cos

When a force is decomposed, if the directions of the two components are known at the same time, then the decomposition of the force has a definite solution. Right or wrong

Correct. Because only one parallelogram can be made at this time, so the solution is unique