Question

If a ball is dropped from rest, what is it’s velocity after 4 seconds

Answer 1

Answer: -39.2 m/s directed downwards

Explanation:

We can solve this problem with the following equation:

$V=V_{o}+gt$

Where:

$V$ is the ball's velocity at 4 s

$V_{o}=0m/s$ is the ball's intial velocity, since it was dropped from rest

$g=-9.8 m/s^{2}$ is the acceleration due gravity, aways directed downwards

$t=4 s$ is the time

Solving:

$V=0m/s-9.8 m/s^{2}(4 s)$

Finally:

$V=-39.2 m/s$ The negative sign indicates the velocity is downwards