Answer
(a) The coconut will strike the ground after $1.43~s$
(b) The coconut will strike the ground a horizontal distance of 25.7 meters from the release point.
Work Step by Step
(a) We can find the time it takes to reach the ground:
$y = \frac{1}{2}at^2$
$t = \sqrt{\frac{2y}{a}}$
$t = \sqrt{\frac{(2)(10~m)}{9.80~m/s^2}}$
$t = 1.43~s$
The coconut will strike the ground after $1.43~s$
(b) We can find the horizontal displacement in this time:
$x = v_x~t = (18~m/s)(1.43~s) = 25.7~m$
The coconut will strike the ground a horizontal distance of 25.7 meters from the release point.
