Because acceleration depends not only on the change in velocity.
It also depends on the time during which the change occurs.
The formula is
Acceleration = (change in velocity) divided by (time for the change) .
Maybe Sla changed his velocity in 3 seconds, but Hazel
took all morning to change hers. In that case, even though
the amounts of change were equal, the times were different,
so the quotients of (change/time) were different.
