Rank Each of the three identical hockey pucks shown in Figure 5.19 is acted on by a 3-N force. Puck A moves
with a speed of 7 m/s in a direction opposite to the
force puck B is instantaneously at rest; puck C moves
with a speed of 7 m/sat right angles to the force. Rank
the three pucks in order of the magnitude of their
acceleration, starting with the smallest. Indicate ties
where appropriate

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

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?

Which is special about a dc circuit ? a. it has both series and parallel components b. it has only series or only parallel components c. charge moves in a single direction d. charge moves back and forth quickly