Suppose a baseball is hit 3 feet above the ground, and that it leaves the bat at a speed of 100 miles an hour at an angle of 20° from the horizontal. I've got the parametric equations in terms of x and in terms of y, and I have values plotted and a graph sketched. My question is in regards to the initial height of 3 ft, and the position of the ball when it hits the ground. Now in looking at the table of these values, the y value (corresponding to height) is equal to zero at some point in time. Now if one were to look at the table of values, and see that the height is equal to zero feet at some point, is it true that this is not actually 0 ft, since we started from 3 feet? And if we wanted to find out when the ball hit the ground, we'd need to find when the ball was at -3 feet?