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

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.