These are some ways how scientists and engineers develop, use and refine models.
1. Imagine. They have to know what exactly trying to model. They have to imagine and brainstorm what are the things to be considered.
2. Reason. Next, they need to answer the questions brought from their brainstorming. They need to be able to reason out.
3. Calculate and Predict. Once they know it, that's the time they can start modelling and calculate - and predict.
When the blood pH is raised and lowered and the source of acid does not involve the respiratory system it is considered metabolic. When there is too much acid in the blood it is called acidosis. When there is too little, it is called alkalosis.
Not a physical change, It's a chemical change because you can't change the process back to its original state. If it was a physical change, you could change it back to its original state using the boiling, evaporating or melting process.
A) Sediment builds up over organisms :)
Land surfaces heat up and cool down faster then water surfaces