Hello,
The answer is to "prove your hypothesis".
Reason:
Researchers do experiments to prove there hypothesis they will most likely do the experiment a few times in older to have the conclusion valid therefore proving his or her experiment.
If you need anymore help feel free to ask me!
Hope this helps!
~Nonportrit
People are asleep at 3 am so energy would be less then.
It's most likely the combination of a bucket and the wheel.