High-strength materials that are able to resist impact usually have high hardness and high elastic moduli, facilitating also high speeds of elastic waves (sound), so that resulting shock waves quickly dissipate impact energy. Based on theoretical considerations, there is a… Read More
The Kapitsa pendulum (an inverted pendulum on a vibrating foundation), which is stabilized due to fast high frequency vibrations of a foundation, is an example of how vibrations can be substituted by an effective force. A mathematical technique of averaging… Read More
The law of rotational dynamics states that the moment of inertia times the angular acceleration equals the applied torque. This is analogous to the 2nd Newton’s law. But can the former be logically deduced from the latter? The rotational law… Read More
Traditionally, Mechanics is divided into three parts: the Statics (a study of forces without regard of motion), Kinematics (a study of motion regardless forces), and Dynamics (the study of forces and motions in combination). Well, this is a continental classification,… Read More
There is a wide-spread misconception about Newton’s laws of motion. Many people believe that all mechanics can be deduced logically from Newton’s laws in a manner similar to how geometry can be deduced from Euclid’s axioms. This is incorrect. By… Read More
A famous Japanese poem, the “Frog Haiku” composed by Bashô in 1686, says: 古池や 蛙飛び込む 水の音 (“Old pond — a frog jumped in — sound of water”). Splashes of water are fascinating phenomena. An award winning photograph “Milk Drop Coronet”… Read More
Some people state that mechanics is not a fundamental science, but rather an applied discipline. I belong to a school of mechanicians, who would strongly disagree with that assertion. For me, mechanics is a part of physics; however, it has… Read More
Another extremely interesting topic in modern physics, which may be related to the study of friction, is the jamming transition. A granular material can flow through a pipe or it can jam. The transition is abrupt, and some scholars have… Read More
This could be a good project for students of dynamics. The tower clock emerges in medieval European cities at about the year 1300 CE: Westminster (1288), Canterbury Cathedral (1292), Salisbury cathedral clock (1306), St. Albans (1326), etc. The pendulum was… Read More
Can you discover a new type of hydrodynamic instability? A UWM colleague from our department, Dr. Robert Balmer, did it almost 50 years ago. The phenomenon is the following: imagine that you have a horizontal pipe partially filled with a… Read More
Among many models which explain the Coulomb-Amontons law of friction, an interesting model is based on the damage rheology. Dr. Vladimir Lyakhovsky, whom I visited recently at the Geological Survey of Israel in Jerusalem, has explained to me the details… Read More