(17-78) Cylinders A (10 lb) and B (5 lb) are connected by a massless cord over a 3-lb pulley (a uniform disk). If the system is released from rest, find the speed of the cylinders 0.5 s later. The cord does not slip on the pulley. What would the speed be if the pulley were massless

Your physics assignment is to figure out a way to use electricity to launch a small 6.0-cm-long plastic drink stirrer. you decide that you'll charge the little plastic rod by rubbing it with fur, then hold it near a long, charged wire, as shown in figure p23.56 . when you let go, the electric force of the wire on the plastic rod will shoot it away. suppose you can uniformly charge the plastic stirrer to 10 nc and that the linear charge density of the long wire is 1.0 x10-7 c/m. what is the net electric force on the plastic stirrer if the end closest to the wire is 2.0 cm away?