grant jumps 4.20 m straight up into the air to slam - dunk a basketball into the net. with what speed did he…

Explanation:

Step1: List known variables

Displacement $s=4.20\ \text{m}$, final velocity $v=0\ \text{m/s}$, acceleration $a=-g=-9.81\ \text{m/s}^2$

Step2: Select kinematic equation

Use $v^2 = u^2 + 2as$ to solve for initial velocity $u$

Step3: Rearrange equation for $u$

$u = \sqrt{v^2 - 2as}$

Step4: Substitute values and calculate

$u = \sqrt{0^2 - 2\times(-9.81)\times4.20} = \sqrt{82.404}$

Answer:

$9.08\ \text{m/s}$