LOG#204. Mechanics and light.

Gravitational or electrical forces are inverse squared laws:         Strikingly similar, they are both also conservative forces. For gravity:     and     for the electrical force. Defining the potentials , and , you get the … Continue reading

LOG#053. Derivatives of position.

Position or displacement and its various derivatives define an ordered hierarchy of meaningful concepts. There are special names for the derivatives of position (first derivative is called velocity, second derivative is called acceleration, and some other derivatives with proper name), … Continue reading

LOG#042. Pulley with variable mass.

This interesting problem was recently found in certain public examination. I will solve it here since I found it fascinating and useful, since it is a problem with “variable mass”. A pulley with negligible mass is given (see the figures … Continue reading