Begin by defining the positive direction. We will call “up” positive. Then use the four-step method to
solve the problem.
Step 1 : Table of variables.
Why do we always indicate what part of the motion the kinematics chart is for? Well, this problem
could be solved instead by making two separate charts: one for the upward motion (where vf would bezero), and one for the downward motion (where v (^) o would be zero). Be crystal clear how much of an
object’s motion you are considering with a chart.
Remember that displacement is a vector quantity. Even though the melon goes up before coming back
down, the displacement is simply equal to the height at which the melon ends its journey (0 m) minus its
initial height (30 m). Another way to think about displacement: In total, the melon ended up 30 m BELOW
where it started. Because down is the negative direction, the displacement is −30 m.
Step 2 : Count variables.