Why is air warmer near Earth's surface? A.
The Sun heats Earth's surface, and in turn the air above it is heated.

B.
Warm air is more dense and sits on top of Earth's surface.

C.
Warm air is less dense and sits on Earth's surface HELP PLZ!!

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.