A pebble is thrown vertically upward from the base of a tower and is observed to be level with the top of the tower after 4.0s. The tower is 60m high. The pebble continues to rise, comes momentarily to rest, and then falls back to the base.
(a) Determine the initial speed of projection.
(b) Calculate the greatest height reached by the pebble above the ground.
(c) Find the total time of flight from projection until the pebble returns to the base.
(d) Evaluate the speed of the pebble when it again passes the top of the tower while descending.
a. (a) Initial speed
b. (b) Maximum height above ground
c. (c) Total time of flight
d. (d) Speed while crossing the tower top downward