Suppose you fire a rifle bullet (speed= 1600 m/s) in a shooting gallery and hear the gong on the target ring 0.731 seconds later. If the speed of sound is 343 m/s, how far away is the target? Hint: the 0.731 s refers to the time it takes the bullet to travel to the target AND the time it takes the sound to travel back.

Irrigation channels that require regular flow monitoring are often equipped with electromagnetic flowmeters in which the magnetic field is produced by horizontal coils embedded in the bottom of the channel. a particular coil has 100 turns and a diameter of 6.0 m. when it's time for a measurement, a 4.5 a current is turned on. the large diameter of the coil means that the field in the water flowing directly above the center of the coil is approximately equal to the field in the center of the coil. the field is directed downward and the water is flowing east. the water is flowing above the center of the coil at 1.5 m/s . what is the magnitude of the field at the center of the coil? what is the direction of the force on a positive ion in the water above the center of the coil? what is the magnitude of the force on an ion with a charge +e?