A rocket is launched with an initial velocity of zero, and with acceleration in feet per second per second defined by:

A rocket is launched with an initial velocity of zero, and with acceleration in feet per second per second defined by:--------( 20e^(-t/2), for 0 <= t <= 10 seconds)a(t) = (--------( -16, for t > 10 seconds)a) At what time does the rocket begin to descend?b) How high does the rocket reach?c) What is the velocity when the rocket impacts the earth?d) Write a formula for the position of the rocket with respect to time for t > 10 seconds.Thanks!