Question

A ball was kicked upward at a speed of 64.2 m/s. How fast was the ball going 1.5 seconds later

Answer 1

The ball's velocity $v$ at time $t$ is

$v=v_0-gt$

where $g=9.81\,\frac{\mathrm m}{\mathrm s^2}$ is the acceleration due to gravity. So after 1.5 seconds, the ball's velocity is

$v=64.2\,\dfrac{\mathrm m}{\mathrm s}-\left(9.81\,\dfrac{\mathrm m}{\mathrm s^2}\right)(1.5\,\mathrm s)$

$\implies v=49.5\,\dfrac{\mathrm m}{\mathrm s}$

so the ball's speed after 1.5 seconds is also 49.5 m/s.