Question

A) How long does it take the ball to reach the maximum height?

Answer 1

recall the formula Vf^2 = Vi^2 + 2ad

write your givens:

Vf = 0 m/s ( this is when the ball is at its highest point)
Vi = 18 m/s (given quantity)
a = -9.81 m/s^2 (the ball is travelling against the pull of gravity.gravity will sooner or later pull the ball back down)
d = ? (the variable you're trying to find)

Vf^2 = Vi^2 + 2ad (isolate for d)
d = Vf^2 - Vi^2/ 2(a) (distance equals final velocity squared minus initial velocity squared, divided by twice the acceleration)
d = (0 m/s)^2 - (18 m/s)^2 / 2(-9.81 m/s^2)
d = 16.5 m to the nearest tenth or 17 m to the nearest one.