A glass rod is rubbed with a piece of silk to give it a positive charge. The rod is then brought near to an uncharged metal sphere supported by an insulated stand. The rod is then removed. What type of charging is used to charge the rod

The bar of prob. 5/82 is repeated here. the ends of the 0.4-m bar remain in contact with their re- spective support surfaces. end b has a velocity of 0.5 m/s and an acceleration of 0.3 m/s2 in the di- rections shown. determine the angular accelera- tion of the bar and the acceleration of end a.