In some areas of the world, like california and japan, earthquakes are a common occurrence. how can this best be explained?
a) the strong ocean currents are undermining both areas causing earthquakes.
b) both areas are subjected to strong ocean wind and waves that causes earthquakes.
c) both areas are located near the edge of the pacific ocean, the unstable sand causes earthquakes.
d) both areas are on the boundary of active plate margins, the motion of the plates causes earthquakes.

What is the magnitude of the resultant vector round your answer to the nearest tenth

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Search coils and credit cards. one practical way to measure magnetic field strength uses a small, closely wound coil called a search coil. the coil is initially held with its plane perpendicular to a magnetic field. the coil is then either quickly rotated a quarter-turn about a diameter or quickly pulled out of the field. (a) derive the equation relating the total charge q that flows through a search coil to the magnetic-field magnitude b. the search coil has n turns, each with area a, and the flux through the coil is decreased from its initial maximum value to zero in a time ∆t. the resistance of the coil is r, and the total charge is q = i∆t, where i is the average current induced by the change in flux. (b) in a credit card reader, the magnetic strip on the back of a credit card is rapidly “swiped” past a coil within the reader. explain, using the same ideas that underlie the operation of a search coil, how the reader can decode the information stored in the pattern of magnetization on the strip. (c) is it necessary that the credit card be “swiped” through the reader at exactly the right speed? why or why not?