Q. The velocity of a falling object in a vacuum is directly proportional to the amount of time the object has been falling. If after 5 seconds an object is falling at a speed of 90 miles per hour, how fast will it be falling after 12 seconds?
Much like your other question, we can use the common ratio to solve this. A direct proportion says that
x/y = some constant
So we've got x = velocity and y = time. Since the object has the same velocity/time ratio the whole time:
90/5 = x/12, or
216 = x
