All bodies in real conditions cannot move at constant speeds, and usually the speed of the body changes over time in both direction and magnitude. Such a movement is called uneven. The simplest non-uniform motion of bodies is a rectilinear uniformly accelerated motion, and its free fall can be considered a vivid example.
The theory of uniformly accelerated movement was developed by Galileo Galilei. It was he who first defined this type of movement, described its laws and proved a number of theorems.
Scientists have studied the movement of physical bodies since time immemorial. Long before Galileo was born, the foundations of kinematics were laid. Now, to determine the path traveled by the body for some time with a known constant speed, any elementary school student can. It is enough to multiply the speed of the body by the time of movement - and the answer is ready!
Difficulties arose as soon as they began to consider the movement of the body with a variable speed, and in fact it almost always happens in life. Look at the arrow of the car’s speedometer - it is constantly in motion and shows that the speed of the car changes almost every minute, or even more often. This problem - how to calculate the path of a body moving at a constantly changing speed - worried the minds of scientists long before Galileo.
After a series of experiments, Galileo showed that the concept of "free fall of the body" is equivalent to the concept of "uniformly accelerated motion."
Today, having ultraprecise time measuring instruments, even a schoolchild can observe the dynamics of a fall. In Galileo's time, ordinary mechanical watches were rare, moreover, inaccurate and primitive. Therefore, the scientist had to create a completely new device, with the help of which the problem of all measurements of values during a fall was solved. Experimenting and changing the conditions of the experiment, making measurements and conclusions, Galileo gradually came to the conclusion that the body, starting at zero speed, moves further, gradually increasing this speed. Translated into the language of mathematics, the uniformly accelerated motion observed by him can be described using the formula a = vt d = (at2) / 2, where v is the velocity, the acceleration of the body is a, d is the distance the body has traveled in time t.
If we observe the fall of bodies and analyze these formulas, then we can say after the scientist:
• the rate of fall with time elapsed from the beginning of the movement even increases visibly;
• if the body makes an equally accelerated movement, then the first half of the path it will take longer than the rest;
• the longer the body “accelerates”, the greater the path it will travel for equal periods of time.
In addition, Galileo Galilei made another rather important conclusion, although he could not confirm it by measurements. He found that the acceleration of gravity g will be almost the same near the surface of the Earth and equal to g = 9.8 m / s2. This value characterizes the fall of bodies near the surface of our planet due to the forces of gravity, therefore it is called the acceleration of gravity or gravitational acceleration.
The results of Galileo's research formed the basis for Newton's later triumphant discoveries and formed the basis of modern classical mechanics. Much later, Newton showed that the acceleration of the body can also be calculated theoretically using the laws of mechanics and the law of universal gravitation that he discovered.
Another no less important conclusion from Galileo's discoveries is that the acceleration of gravity is completely independent of mass. This practical conclusion was completely contrary to all previously existing claims of natural philosophers. After all, they argued that every thing aspires to the center of the universe (and the Earth, in their opinion, was this center) and the more massive the object, the faster it does it.
Of course, Galileo made his conclusions on the basis of experiments. But it is unlikely that the scientist carried out the experiments attributed to him, dropping various objects from the “falling” tower in Pisa, supposedly demonstrating that all of them will fall to the surface of the Earth at the same time. We can only say with confidence that Galileo knew for sure: heavier objects will fall to the ground faster due to the air resistance acting on them. But people tend to invent fables.