Levels And Rates

Question 1

Rates

Answer 1

No memory

Can be changing

Question 2

Levels

Answer 2

Have memory

Must have initial value

Question 3

rates =

Answer 3

Derivatives

Question 4

Levels =

Answer 4

Integrals

Question 5

Things to remember (1)

Answer 5

1) a level May have a direct influence on a rate
2) An inflow rate with a negative numerical value is the same as an outflow rate with a positive number
3) the state of a system is an INSTANTANEOUS concept and is determined only by the levels at that point in time

Question 6

Things to remember (2)

Answer 6

4) mathematically, the value of a level is equal to its initial value plus the integral of the net rate (inflow rates minus outflow rates)
5) the units for rate must always have time in the denominator (explicitly or implicitly)
6) a level may represent a rate of some other quantity.
(E.g. speed is a rate in terms of distance, but speed can also be a level where the rate is acceleration)

Question 7

Things to remember (3)

Answer 7

7) units of a level must be dimensionally equivalent to the units of the rates multiplied by time
8) auxiliary variables may be used to represent fixed quantities or functions to perform calculations
(E.g. drug clearance (a numerical constant); body temperature)

Question 8

Riemann sum

Answer 8

Determining the accumulated quantity resulting from some net rate