Which of the following is another way to say that, in energy transforms, some energy is always converted unusable or unwanted forms?

a. the entropy of a system tends to decrease overtime.
b. energy transforms are never 100% efficient
c. the energy in a system is always constant
d. energy transfers are always 100% efficient

increase masses, decrease separation

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)