1. Mike wears an 8.50 kg backpack while scaling a cliff. After 90 minutes, Mike is 11.2 m above the starting point. a. How much work does Mike do on the backpack?
b. If Mike weighs 630 N, how much work does he do lifting himself and the backpack?
c. What is the average power developed by Mike?

Two 2.0-cm-diameter disks face each other, 1.0 mm apart. they are charged to ±10 nc. what is the electric field strength between the disks? a proton is shot from the negative disk toward the positive disk. what launch speed must the proton have to just barely reach the positive disk?

What energy transformations occur each time the skateboarder rolls up the ramp?

The ideal gas model is valid if which of the following conditions is true? the gas density is low. the gas density is high. the temperature is low. the temperature is high. the gas density and the temperature are low. the gas density and the temperature are high. the gas density is high and the temperature is low. the gas density is low and the temperature is high.