I lift a 20kg ball up 2.5 meters off the ground on Earth.

-Earth’s gravitational acceleration is about 9.8 m/s2.

a) How much gravitational potential energy does the ball have at this point?

b) How much work did I do lifting up the ball?

c) If I lift the same ball the same distance on the Moon, then how much gravitational potential energy will it have? (Moon’s Gravity = 1.6 m/s/s)

The heater element of a 120 v toaster is a 5.4 m length of nichrome wire, whose diameter is 0.48 mm. the resistivity of nichrome at the operating temperature of the toaster is 1.3 × 10-6 ω·m. the toaster is operated at a voltage of 120 v. (a) what is the power drawn by the toaster? (b) if the cost of electricity is 12 ¢ per kilowatt-hour, and it takes 2 minutes to toast bread, how much does it cost for toasted bread? (c) when the heater element is at room temperature, is the resistivity in the nichrome wire greater than, less than, or equal to it’s resistivity when at operating temperature? explain.