Question

Calculate the acceleration of an airplane that starts at rest and reaches a speed 45m/s in 9 seconds

Answer 1

Here's the explanation of HOW to find the answer. That's much more important than the answer.

The two BOLD lines are the parts you need to remember. They're the things you LEARN when you STUDY. If you remember them, then you can solve almost ANY acceleration problem.

Acceleration = (change in speed) / (time for the change)

Change in speed = (speed at the end) minus (speed at the beginning)

Change in speed = (45 m/s) minus (zero)

Change in speed = 45 m/s .

Acceleration = (45 m/s) / (9 sec)

Acceleration = 5 m/s²

Answer 2

I believe the acceleration would be 5m/s

All you would need to do is divide the final speed by the time it took to get there. I am only about 80 sure this answer is correct, so take my advise only if you feel comfortable.