Study the scenario.

as a spacecraft moves beyond pluto, its thrusters are turned on for a short time to boost its speed to approximately 32,500 mi/h. the thrusters are then turned off.

if no other forces ever act on the spacecraft what will it do?

it will continue moving in the same direction, but it will speed up because there are no forces to slow it down

it will continue moving at 32,500 mi/h the same direction because forces are not required for an object to continue its motion

it will stop immediately because a force is needed constantly for it to move at all

it will continue moving in the same direction, but it will gradually slow down because a force is needed to maintain its speed.

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?