in which situations is work being done?
a. hannah leans against her locker, but it doesn’t move.
b. andy’s car rolls down a hill with the engine off.
c. a wind turbine stands still on a sunny, windless day.
d. a balloon expands as it is heated by the sun.
e, james pedals a stationary exercise cycle that doesn’t move.

What sentence best supports the statement that hormones are involved in the regulation of homeostasis? a. the hormone erythropoeitin increases the production of red blood cells when oxygen levels are low. b. the hormone oxytocin promotes labor contractions of the uterus during childbirth. c. the hormone melatonin induces sleep and its production is slowed by exposure to light. d. the hormone cortisol suppresses the immune system and is produced when the body is under stress.