On planet Delta a ball is thrown upward from a height of 50 meters with an initial velocity of 21 meters per second. The height of the ball at time t seconds is given by s(t) =-2t? + 21t + 50. Use proper units! (a) Find the average velocity over the time interval [4,9]. (b) Find the instantaneous velocity at time t=9. Was the ball moving upward or downward at that time? (c) Find the acceleration at time t =9.

A potato is launched vertically upward with an initial velocity of 170 feet per second from a potato gun at the top of an 66-foot-tall building. The distance in feet that the potato travels from the ground after t seconds is given by s(t) 16+2 + 170t + 66. a) Find the velocity of the potato after 2.2 seconds and 7 seconds. At t = 2.2 seconds, v = At t = 7 seconds, v = feet per second. feet per second. b) Find the speed of the potato at 2.2 second and 7 seconds. At t = 2.2 seconds, the speed of the potato is At t = 7 seconds, the speed of the potato is c) Determine when the potato reaches its maximum height. t seconds Determine how long the potato is in the air. seconds. d) Find the acceleration of the potato at 2.2 seconds and 7 seconds. At t = 2.2 seconds, a = At t = 7 seconds, a = feet per second. Determine the velocity of the potato upon hitting the ground. feet per second. feet per second. feet per second per second. feet per second per second.