What is fluid friction?
A. When two solid surfaces slide past one
another
B. When air, water, or oil flow next to a solid.
C. When an object rolls across a surface.
D. When objects move through sand.

When it is summer at the south pole, a. the northern hemisphere is tilted toward the sun. b. the southern hemisphere is tilted away from the sun. c. the northern hemisphere is tilted away from the sun. d. both the southern and northern hemispheres are tilted toward the sun.