Dolphins can use sonar to detect objects in the sea. How far away is the object from the dolphin if the sonar takes 1 sec to be returned? Sound travels at 1484 m/s in sea water.

Learning goal: to understand that the charge stored by capacitors represents energy; to be able to calculate the stored energy and its changes under different circumstances. an air-filled parallel-plate capacitor has plate area a and plate separation d. the capacitor is connected to a battery that creates a constant voltage v.