P. 4711. Six alike simple pendulums are made of electrically insulating threads of negligible mass and of small metal spheres of mass 5 g. The length of each pendulum is 0.5 m. The six pendulums are hung at the same point, and then they are all rotated about a vertical axis through this point. After a long enough time each small sphere revolves along a circular path of radius \(\displaystyle r\) in a horizontal plane.
\(\displaystyle a)\) What is the radius \(\displaystyle r\) of the path, if the period of the motion is 1 s?
\(\displaystyle b)\) What same amount of charge should be added to the spheres in order that they stay at the circumference of the same radius of circle \(\displaystyle r\), without rotation?
Deadline expired on 10 March 2015.