If a ball is thrown vertically upward with a velocity of 128 ft/s, then its height after t seconds is s = 128t − 16t2.
(a) what is the maximum height reached by the ball?
(b) what is the velocity of the ball when it is 240 ft above the ground on its way up? (consider up to be the positive direction.)
(c) what is the velocity of the ball when it is 240 ft above the ground on its way down?

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?