Make an observation.
Conduct research.
Form hypothesis.
Test hypothesis.
Record data.
Draw conclusion.
Replicate.
One thing that is designed to change in the set up of the experiment. ( The things that I can change) Independent Variable.
Cruising at 35,000 feet in an airliner, straight toward the east,
at 500 miles per hour.
Since your speed is not changing and you're moving in a straight line,
your acceleration is zero.