Someone throws a ball upward with an initial velocity of vi. use the free fall equations to determine and show the final velocity vf the ball has when it returns to the height from which it was released (hint you want a final equation that contains those two variables and no others). (further hint: what hidden information can you get from the phrase ""returns to the height from which it was released""? ) ignore air resistance.

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?