A ball is kicked up from a platform. The height of the ball above the ground (measured in meters) can be modeled by the function, h(t) = 4.5 + 18t - 4.8t?
where t represents the amount of time (in seconds) since the ball was kicked. When does the ball reach the ground?
O 1.875 seconds
O 2 seconds
O 3.985 seconds
O 21.375 seconds

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)