Chapter 6

Question 1

What is a mass balance check?

Answer 1

It ensures that no matter appears or disappears from the system. This is based on first principles.

Question 2

What are the three types of boundaries and how do they differ?

Answer 2

1. Open boundaries: Fluxes have no effect on the environment. Env has an infinite capacity to absorb or exchange fluxes.
2. Closed boundaries: There is no exchange at all. This idea is used to minimise fluxes as it is an ideal situation.
3. Mixed boundaries: In a simple linearised situation the boundary of a system is characterised by a resistance between the heart of the system and the external environment. - most frequently occurring

Question 3

What are first principles?

Answer 3

The laws of conservation of mass, energy and momentum are usually referred to by first principles.

Question 4

What are the precisions of variables stored in computers?

Answer 4

1. single precision, 32 bits to store a floating point value
2. double precision, with 64 bits to store floating point value
   It is more precise to use 0.1 kg instead of 100g