The 11th chapter of Flash Basic Theory class collision Physics Ⅰ

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We all want technical books that can sneak deep, from simple to complex. The complexity of the content in this chapter reaches its peak. It's not that the next chapters are going to get easier, but I hope you don't cut corners when you're learning this chapter. I will take you step-by-step to learn the concept of this chapter, if so far everyone can keep up with my pace, that would be better.

In this chapter we want to focus on momentum: what happens to the momentum of two objects after a collision, the conservation of momentum, and how to apply momentum in ActionScript.

The object used in the example of this chapter is this simple direct principle, which is usually referred to as "billiard Physics". We will soon see some examples of collisions of billiard balls of different sizes.

When I give you the code, I start with a simple one-dimensional motion, so I can easily understand it. And then transition to two-dimensional coordinates, such as the coordinate rotation of the previous chapter. Essentially, the two-dimensional scene is rotated into a plane. In the end, you can ignore one axis and operate on only one dimensional scene. These all make the reader look forward to the next content. Let's start with quality and momentum.

Quality

The previous chapters of this book discuss several concepts of motion: velocity, acceleration, vector, friction, bounce, easing, elasticity, and gravity. And I managed to steer clear of the quality of the object. Now we are going to reopen this question, and strictly speaking, there are several places in the book that have to incorporate quality into the equation. I usually only care about making the object look right, focusing on the system to make the right effect. The most important thing is that the execution results must be very efficient and cannot let the program destroy Flash.

However, from now on the quality problem can no longer be ignored. The mass of an object is closely related to momentum, so we have to confront it directly.

What is quality? On Earth, we generally think that mass is the weight of an object. They do have a close relationship, because weight and mass are proportional. The greater the mass of an object, the greater its weight. In fact, we use the same unit of measurement for mass and weight: kilograms, pounds, and so on. Strictly speaking, Mass is the unit of measure that the object is subjected to the speed.

Therefore, the larger the mass of an object, the harder it is to move and it is not easy to change its own motion (slowing, accelerating, or changing direction).

The mass is also associated with acceleration and force. The greater the mass of an object, the greater the force it will give it to accelerate. My Chevy Cavalier [Note: The name of a car] the engine can generate enough force for the car as an acceleration. However, such forces are far from sufficient for the acceleration of a large truck. Because the quality of the truck is relatively large, the engine needs more force.

Momentum

Now look at the momentum. It is composed of the mass and velocity of the object, the product of the mass and the speed. Momentum is usually expressed in the letter p, the mass is expressed in m, and the speed is expressed in V. The following formula should not be explained:

p = m * V

In other words, the mass is small, the momentum of the big speed is similar to the momentum of small mass velocity. The big trucks that are moving at 20 mph are enough to kill people. In addition, the quality of the bullet is very light, but the speed is very fast, but also fatal.

Since Velocity v is a vector (direction and magnitude), the momentum must also be a vector. The vector of momentum is the same as the vector of the velocity. To fully describe the momentum, we can say:

5 kg * 20 m/s angle is 23 degrees in the direction of movement.

It's complicated, isn't it? Now you know why I have to wait here to say it.