Two round concentric metal wires lie on a tabletop, one inside the other. The inner wire has a diameter of 19.0 cmcm and carries
a clockwise current of 20.0 AA , as viewed from above, and the outer wire has a diameter of 38.0 cmcm .What must be the direction (as viewed from above) of the current in the outer wire so that the net magnetic field due to this combination of wires is zero at the common center of the wires? What must be the magnitude of the current in the outer wire so that the net magnetic field due to this combination of wires is zero at the common center of the wires?
A billiard ball moves with 3 kg⋅m/s of momentum and strikes three other billiard balls that have been just sitting there at rest and not moving.
The total momentum of all four balls after the collision is <em>3 kg⋅m/s</em>, because momentum is not created or destroyed. The total amount of it after an event is the same as the total amount of it before the event.
Since work is the change in kinetic energy, the efficiency of a machine can be stated as the percentage of the output work divided by the input work minus the work lost from to friction and heat. Multiply Eff by 100% to get the efficiency percentage.
