Fluctuations are one of the common types of mechanical movement. The most obvious example is the oscillations that a physical pendulum performs. This is a heavy body fixed on a thread at one point. Moving the pendulum away from the equilibrium position and letting it go, we allow it to fall, but the fall does not occur freely, but along a path equal to the length of the thread.
Here you can observe the process of converting potential energy into kinetic energy and vice versa. By rejecting the physical pendulum, we ask it the potential energy. Then, when he is released, he begins to move, and when he returns to the equilibrium point, his speed will be maximum. In the process of moving downward, a part of the potential energy is converted into kinetic energy. Further, moving by inertia, the body rises higher and higher until at some point the movement stops. Here kinetic energy is converted again into potential.
Then the pendulum begins to move in the opposite direction, and everything repeats. Thus, we see that the physical pendulum oscillates due to the ongoing transitions of potential energy into kinetic energy, and then back. The time spent on the entire oscillation, i.e. that during which the body, having left from any point of the trajectory of its movement, will return there again, is called the period of oscillations. The greatest deviation from the equilibrium point of the pendulum is called the oscillation amplitude.
Studying the oscillations, scientists found that the period of the physical pendulum with which it oscillates is not connected in any way with the mass of the pendulum and is determined only by the length of the string and the value of the acceleration of gravity. The occurrence of oscillation is possible in the case when the load is fixed on the spring. In this case, the potential energy of the compressed spring passes into the kinetic energy of the movement of the load and vice versa.
Fluctuations made by a physical pendulum or load on a spring, if there is no influence of additional forces, are called free or own. If any external influence occurs on them, then such oscillations are called forced. With prolonged exposure to an external additional periodic force, the pendulum begins to oscillate with the frequency of exposure to this force. With this effect, a phenomenon such as resonance may occur.
Working with a pendulum is extremely interesting and can help in solving many problems. It is enough to recall the Foucault pendulum, thanks to which it was possible to prove that the Earth rotates. In this experiment, the movement of the pendulum was observed. For this, a load suspended on a wire 67 meters long was used. According to the plan, only the gravitational force of the Earth and the tension force of the wire acted on the pendulum. As a result, the oscillations should have occurred only in a vertical plane.
There was sand on the floor and the pendulum with its sharp end during movement left its mark on it. It turned out that the movement is carried out not only in the vertical plane, but there is also a horizontal component. With each movement of the pendulum, the deviation was about three millimeters from the previous trajectory, in an hour the plane in which the pendulum was vibrating turned eleven degrees.
You can recall the use of the pendulum in the watch, based on a constant period of its oscillations. This period depends only on the length of the pendulum. The accuracy of such watches can be significant. In 1954, a Soviet engineer Fedchenko created a pendulum clock with an accuracy of 0.0003 s per day.
This is how you can describe what a physical pendulum is, its properties and parameters, the possibilities for its use in science and technology.