A rock thrown vertically upward from the surface of the moon at a velocity of 8 m/sec reaches a height of s = 8t - 0.81- meters in t sec. a. Find the rock's velocity and acceleration at time t. b. How long does it take the rock to reach its highest point? c. How high does the rock go? d. How long does it take the rock to reach half its maximum height? e. How long is the rock aloft? a. Find the rock's velocity at time t. V= m/sThe accompanying figure shows the velocity v=t(t) ofa particle moving on a coordinate line. {a} When does the particle move forward? move backward? speed up? slow down? (bl When is the particle's acceleration positive? negative? zero? (c) When does the particle move at its greatest speed? (d) When does the particle stand still for more than an instant? (a) When does the particle move fonvard? Type an equation or a compound inequality Type an expression using t as the variable. Use a comma to separate answers as needed.)