15 points if you hold a bar magnet in each hand and bring your hands together, will the force be attractive or repulsive if the magnets are held: (ref: p.650-657)
a) with the two north poles together?
b) with a north pole and south pole together?

The summit of chimborazo, in ecuador, which is at a distance of about 6,384 km from the earth’s center. the bottom of the mariana trench, in the western pacific ocean, which is nearly 6,370 km from the center of the earth. on the surface of earth on the equator line.

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.

What’s #16 asking me and how do i solve it?