A surveyor is using a magnetic compass 5.4 m below a power line in which there is a steady current of 110 A. Compared to a typical value for Earth's magnetic field of 20 μT, the magnetic field due to the power line is significant and would interfere with the compass reading. What is the magnetic field at the site of the compass due to the power line?

The material that keeps its new shape after it is stretched is called?

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?

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