Suppose an object is fired vertically upward from the ground on Mars with an initial velocity of 90 ft/s. The height s (in feet) of the object above the ground after t seconds is given by s = 90t - 5t2. a. Determine the instantaneous velocity of the object at t = 1. b. When will the object have an instantaneous velocity of 12 ft/s? c. What is the height of the object at the highest point of its trajectory? d. With what speed does the object strike the ground? a. The velocity of the object at time t is given by the function v(t) = The instantaneous velocity of the object at t = 1 is (Type an integer or decimal rounded to the nearest tenth as needed.) b. The object will have an instantaneous velocity of 12 fu/s after (Type an integer or decimal rounded to the nearest tenth as needed.) c. The height of the object at the highest point of its trajectory is (Type an integer or decimal rounded to the nearest tenth as needed.) d. The object strikes the ground with the speed (Type an integer or decimal rounded to the nearest tenth as needed.)