"angry birds", I believe many people have downloaded, now many platforms have, IPhone, Android, PC, PSP, heard that Microsoft's WindowsPhone7 platform version is also fast. It doesn't matter if you haven't played it. The simple idea is to launch a few birds with a slingshot (they look angry), just like throwing a curve like a softball. The goal is to knock the green pigs across the opposite side. It's so simple.
recently, an egg player has questioned the game: from a physical point of view, are the accelerations in the vertical direction of these birds constant? In the horizontal direction? He uses the Tracker Video analysis software to analyze the flight path of a bird after a slingshot is shot, and then again Finally, a conclusion is drawn based on the analysis of mechanical principles. What is the conclusion? Don't worry. Let's take a look at some of his analysis first. The principle of
"Tracker Video analysis" is to mark two "feature objects" in a video at the same time, and to track these two objects from beginning to end. By tracking the location of the two objects in each frame of the video, Tracker will measure, calculate and generate the required data.
another thing that needs to be known is scale. How big is the scale? Who knows? Let's start with a target that appears in every link - the catapult used to launch birds. I first set the height of this catapult to 1 AB.
set scale
and return to data. The map below shows the horizontal direction (x) position of the bird over time.
mapping
What does this map mean? Simply, it means that the bird is moving at a constant speed in the direction of the horizontal X axis. In my experiment, the horizontal velocity of the bird is 2.46 AB/s (assuming that the motion in video is real time). Is that enough? Well, suppose this is a real physical phenomenon, and it is a real parabolic motion. So in this experiment, the drawing of the bird in the hollow will be the following:
the force schematic
that's right, it's so simple. The only force of the bird (in the air) is the earth's gravity, assuming that the bird does not move too fast. This is also the mistake I have seen among many beginners. They always try to exert greater force in the horizontal direction, because they feel that birds are flying in this direction. Don't do that! Aristotle may have made you think so, but you don't want to join his club. In this case, there is no horizontal directional force - no air resistance.
then look at the vertical movement?
graph
Oh, I forgot to point out that there are some missing data in this chart, when the bird "flies out" the screen. In fact, in this case, uniform acceleration is still in the vertical direction (because the graph is fully in line with the two equation). The motion equations involved here are: the
motion equation
the factor of "T2" in the above equation is the 1/2 of the acceleration, which means that the bird's acceleration (in the vertical direction) is "2AB /s2". But what if the bird is really on earth? On earth, the acceleration of gravity in the vertical direction is "9.8 m/s2". Then I can figure out the height of the catapult.
what a big slingshot! Wow, it's about 5 meters high! Then, how big is this red bird by proportion? About 70 centimeters tall! A big bird! A big and angry bird! "