Can you please show step by step how to solve this. Thanks.

III) The position of a particle at time t seconds is given by s - f(1) - 213 - 21/2 + 60r, where s is measured in feet. a. Find the time (t) when the velocity of particle is zero. ANSWER: 1 = 2sec and t = 5sec. b. Determine the acceleration of the particle when its velocity is zero. ANSWER: a(2) = -18f1/s2 and a(5) - 18ft/s2. IV) A child is riding a Ferris wheel. Her height after t seconds, measured in feet, is given by h(t) -25 + 20sin 20 1. What is the child's vertical velocity at time t? ANSWER: v(t) - h'(t) = ncos ( 20 1) 2. What is her vertical velocity at time t = 10? ANSWER: v(10) =0 3. What is her vertical acceleration at time f - 10? ANSWER:a(10) = h"(10) =25- 3