All bodies in the real world can not move with constant speed, the speed of the body and usually change with time, and the direction and magnitude.Such a motion is called uneven.The simplest non-uniform motion of bodies is uniformly accelerated rectilinear motion, and it can be regarded as a shining example of a free fall.
developed theory of uniformly accelerated motion, Galileo Galilei.It was the first time he gave a definition of this kind of movement, described by its laws and proved a number of theorems.
Scientists studied the motion of physical bodies since time immemorial.Long before the birth of Galileo laid the foundations of kinematics.Now determine the path traversed by the body for some time with a known constant speed, can any elementary school student.It is enough to multiply the speed of the body on the move - and the answer is ready!
difficulties arose as soon as the movement of the body began to consider a variable rate, and in fact in life it happens almost always.Look at the speedometer the car - she is constantly on the move and shows that the vehicle speed is changing almost every minute, and even more often.This problem - how to calculate the path of the body is constantly changing speed - worried 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, with ultra-precise measuring instruments of time, be able to observe the dynamics of the fall of even a schoolboy.In the days of Galileo conventional mechanical watches were rare, and the inaccurate and primitive.Therefore, scientists had to create an entirely new device, with which the problem of measuring values in the fall has been resolved.Experimenting and changing conditions of the experiment, making measurements and conclusions, Galileo gradually came to the conclusion that the body, starting with zero velocity, moving on, gradually increasing the speed.Translated into the language of mathematics they observed uniformly accelerated motion can be described by the formula a = vt d = (at2) / 2, where v - velocity, acceleration of the body - a, d - the distance that has passed the body of the time t.
If you watch the falling bodies and analyze these formulas, it is possible after scientists claim:
• speed drop over time, since the beginning of the movement, even visibly increases;
• if the body performs uniformly accelerated motion, the first half of the path it will take longer than the remaining part;
• longer "dispersed" the body, the greater the path it will take for the same period of time.
In addition, Galileo made one rather important conclusion, however, could not confirm the measurements.He found that the gravitational acceleration g will be almost the same near the Earth's surface and is equal to g = 9,8 m / s2.This value characterizes the fall of bodies near the surface of our planet due to gravity forces, so it is called gravitational acceleration and gravitational acceleration.
results of the research of Galileo were the basis for the later triumphant discoveries of Newton and formed the basis of modern classical mechanics.Much later, Newton showed that the acceleration of the body can be calculated theoretically using the discovery of the law of mechanics and the law of gravity.
Another equally important conclusion of the discoveries of Galileo - the acceleration of gravity does not depend on the mass.This practical conclusion completely contrary to all pre-existing natural philosophers claimed.After all, they argued that every thing tends toward the center of the universe (and the earth, in their view, this was the center) and the more massive the object, the faster he does it.
course, Galileo made its findings based on experiments.But it is hardly a scientist conducted experiments attributed to him, throwing a "falling" tower g.Pize various items, supposedly demonstrating that all of them will fall to the surface of the Earth at the same time.We can only say with certainty that Galileo knew for sure: the heavier objects fall to the ground more quickly because of the action of the air resistance.But people tend to invent stories.
