A coil of radius r is made of N circular loops. It is connected to a battery of known emf and internal resistance. The coil produces a magnetic field whose magnitude at the center of the coil is B→.What physical quantities can you determine using this information? (2):The resistance in the circuit / the magnetic dipole moment of the coil / the current in the circuit / the Earth's magentic fieldFrom the two, determine their physical quantities?

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