A roller coaster uses 800 000 J of energy to get to the top of the first hill. During this climb, it gains 500 000 J of potential energy and pauses (velocity = 0) for a fraction of a second at the

very top before heading down the other side.

a) Draw a Sankey diagram for the roller coaster’s climb.

b) What's the kinetic energy at the very top? How do you know?

c) What would be the "useful energy" during its climb to the top? How do you know?

d) How much energy was lost due to friction? (Use Ebefore = Eafter).

e) Calculate the efficiency of the roller coaster during this part of the ride (the climb).

iron would move it is magnetic there is a mag field around the current in the wire

it has to be b, about 97 percent.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia