Mass/volume is the formulae
Elastic
Explanation is that it is force which is snapping back
All isotopes of the same element have the same number of protons
in the nucleus of their atoms, but different numbers of neutrons.
Distance from the reference point
Answer:
The scientific method
Make an observation.
Ask a question.
Form a hypothesis, or testable explanation.
Make a prediction based on the hypothesis.
Test the prediction.
Iterate: use the results to make new hypotheses or predictions.
Explanation: