You create a transformer by wrapping wire around an iron nail. the number of turns are: primary (500); secondary (2500). the primary voltage is 3.00 v. the secondary current is 200 ma. this is like examples #14 and #15 (pages 16 & 17) of chapter 21 notes. 13) calculate the secondary voltage (v). 14) calculate the primary current (a).

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm