Answer:
7.6 s
Explanation:
Considering kinematics formula for final velocity as

Where v and u are final and initial velocities, a is acceleration and s is distance moved.
Making v the subject then

Substituting 8.8 m/s for u, 138 m for s and 2.45 m/s2 for a then

Also, v=u+at and making t the subject of the formula

Substituting 27.45 m/s for v, 8.8 m/s for u and 2.45 m/s for a then

Therefore, it needs 7.6 seconds to travel
Where danger is and how to avoid it as well as to locate other whales
To determine the speed relative to the ground, since the ground is our reference frame, it would be v = 0, for the kid on the skateboard, you would need to take into account the speed that he/she is going and the speed of the keys thrown at.
I believe.
The standard measurement system used by the scientists is called: International System Of Units, or SI. The units of measurement of a few physical quantities are considered to be base units. (Also do you need the base units too cuz I can help you with that) :)