On August 4, 2007, NASA's Phoenix Mars Lander was launched into space to search for life in the icy northern region of the planet Mars; it touched down on Mars on May 25, 2008. As the ship raced into space, its jet fuel tanks dropped off when they were used up. The distance one of the tanks falls in t seconds is modeled by the function

s(t) = 16t2

where s is measured in feet per second and t = 0 is the instant the tank left the ship. Use the function s to find the average speed of a tank during the following time intervals.

(a) The first 10 seconds after separation from the ship

_____ ft/s

(b) The first 50 seconds after separation from the ship

_____ ft/s

1 answer

From a Physics point of view, this question is really flawed.
First of all, it should be -16t^ (gravity works downwards, not upwards)
Secondly, at the moment of jettison of the tanks, the tank still has an upwards velocity, so there should be term in t after the -16t^2

anyway, a "dumb-downed" solution might be

at t = 0 , s(0) = 0 , (not true at all)
at t = 10, s(10) = -16(100) = 1600
avg velocity = (1600=0)/(10-0) = -160 ft/sec

repeat for t = 0 and t = 50