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Forces, moments, energy: important concepts with which to explain the mechanisms we find in nature, from the simplest gestures of our daily life up to the movements of celestial bodies
The closer you are to the pole, the faster you go, while the further away you are from it, the slower you go because speed is related to the distribution of body mass around the axis of rotation. This depends on one of the great laws valid throughout the Universe: the conservation of angular momentum. The ice skater and the planets around the Sun all obey the same law! Nice isn’t it?!
Thanks to the conservation of kinetic energy and momentum that occur in an elastic central collision, moving a few spheres at the end of the row with the stick involves the movement of as many spheres at the other end.
If you turn on the airflow and place a ball on it, it won’t fall even if you tilt the tube. In fact, the speed of the outgoing air creates a small area of depression which surrounds the ball and which always keeps it in the center of the air flow.
The levers are simple machines, capable of “amplifying” human strength, allowing us to carry out jobs with less effort. Not all levers are the same: experiment directly with which lever you can lift the same weight more easily.
If you turn on the airflow and place a ball on it, it won’t fall even if you tilt the tube. In fact, the speed of the outgoing air creates a small area of depression which surrounds the ball and which always keeps it in the center of the air flow.
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You realize that the closer you are to the handle, the faster you go, while the farther you are, the slower you go.
While rotating the physical quantity called angular momentum remains constant. The angular momentum is the product of the rotating speed with a quantity that considers the mass distribution with respect to the rotating axis (the momentum of inertia). Therefore if the distance between the mass and the rotation axis decreases, the rotation speed increases and vice versa.
The shock will be transmitted from the spheres we’ve moved through the intermediate ones, in order to move the ones on the other side. Newton’s cradle’s rule is the following: the same amount of spheres lifted on one side will always be released on the other side, even if the number of spheres is more than half of the total quantity.
This is typical of the so-called elastic collisions, in which kinetic Energy and momentum are maintained. This is an example of nearly elastic collision, in fact, because of friction, slowdown occurs and not perpetual motion.
