When a fixed amount of ideal gas goes through an adiabatic expansion: a. its internal (thermal) energy does not change.
b. the gas does no work.
c. no heat enters or leaves the gas.
d. its temperature cannot change.
e. its pressure must increase.

The cheetah is considered the fastest running animal in the world. cheetahs can accelerate to a speed of 20.1 m/s in 2.50 s and can continue to accelerate to reach a top speed of 28.1 m/s. assume the acceleration is constant until the top speed is reached and is zero thereafter.1) starting from a crouched position, how long does it take a cheetah to reach its top speed? (express your answer to three significant figures.) s2) how far does it travel in that time? (express your answer to three significant figures.) m3) if a cheetah sees a rabbit 120 m away, how long will it take to reach the rabbit, assuming the rabbit does not move? (express your answer to three significant figures.)