<span>In general, the height of a projectile is given by
</span>
<span>
where </span>
is the height at time 
of a projectile shot upward at velocity 
from initial height 
<span>.
The acceleration of gravity </span>
<span> We give it a negative sign in the equation because it pulls down.
Let's apply it to each group.
Group A launches a tennis ball straight up with an initial velocity of 19 meters per second.
We have MKS units, positive (upward) velocity and an initial height of 0.
</span>
<span>
Group B launches a tennis ball straight up with an initial velocity of 50 feet per second. Not metric, velocity +50, initial height zero.
</span>
<span>
Group C drops a tennis ball from a height of 19 meters.
MKS, initial height 19, initial velocity zero.
</span>
<span>
Group D drops a tennis ball from a height of 50 feet.
</span>
<span>
</span>
</span>
<span>
where </span>
The acceleration of gravity </span>
Let's apply it to each group.
Group A launches a tennis ball straight up with an initial velocity of 19 meters per second.
We have MKS units, positive (upward) velocity and an initial height of 0.
</span>
<span>
Group B launches a tennis ball straight up with an initial velocity of 50 feet per second. Not metric, velocity +50, initial height zero.
</span>
<span>
Group C drops a tennis ball from a height of 19 meters.
MKS, initial height 19, initial velocity zero.
</span>
<span>
Group D drops a tennis ball from a height of 50 feet.
</span>
<span>
</span>