2. 1. A model is an artificial re-creation of
an object and should behave in the
same way as the real thing e.g. a
model of a sports car built for testing
a wind tunnel
2. A simulation is when the model is
used to carry out an activity that
mimics real life – when designers
use a model to stimulate what will
happen when the bridge is actually
used.
3. A computer model is created using
programmed instructions and
equations e.g. a computer model of
the way an aircraft behaves when in
flight.
1. any model or simulation is
only as good as the rules,
programmes and
equations it is based on.
2. Its important to test the
model, using situations
where the actual results
are known.
3. In this way the model and
simulation can be
improved.
Limitations of modelling

3. 1. Dangerous events can be studied, e.g.
the effect of a nuclear explosion
2. The model can be used to make
predictions e.g. the speed at which a car
loses control on a bend.
3. Running a simulation may be cheaper
than using the real thing e.g. crashing a
car.
The Ups
1. The model might not be an accurate
representation of the real world – so the
simulation might give misleading results.
2. Producing an effective model might be
time-consuming – and running the
simulation might require expensive
hardware and software.
The Downs

4. 1. Spreadsheets use formulas to try to describe the rules that a real world
object seems to follow. Input values can then be processed using these
formulas to produce output values.
2. Spreadsheets can be used to carry out a what-if analysis. This is when
the user changes input values to see the effect on the output of the
model. So companies can ask questions like, “what would be the effect
on profits if I invested this much money on new machinery?”
3. The output can be in the form of graphs and charts to make the
predictions of the model easier to understand.
Three Reasons why Spreadsheets make Good Models

5. The sorts of what-if questions could be:
• 'If the cost of food rises by 10%, how much will that decrease the profit we
make for the school fete?“
• "If I reduce the number of staff in my business by two, what effect will that
have on the profit at the end of this month?"
• Trying out different scenarios like this is called 'modelling'.
Modelling works well in spreadsheets because all of the calculations have
been set up using formulas. So, when you change one value e.g. food cost,
all of the values related to it, e.g. food cost, total costs, profit will change
automatically.

6. A model has 4 main characteristics that allow in to manipulate numbers and
text. These features allow the model to recalculate values when a number
changes. These featured are:
• variables – is an identifier associated with a particular cell. Within the cell
there will be a particular value.
•Formulae – is the way that a calculation is represented in a spreadsheet.. It
uses numbers, and mathematical operations
•Rules – set of procedures that must be followed. Can also be a sequence of
events required for the calculation to work.
•Functions – used to represent a formula that is too complex or too long to
expect an ordinary user to enter.
e.g. SUM: add a range of cells and gives the total.
MAX: gives maximum value from a list

7. • A computer simulation is a special type of computer model which recreates a
system, that might exist outside the computer.
• Often used to train people how to deal with situations that are too difficult, expensive
or dangerous to recreate and practise for real.
• One example of a simulation is a flight simulator.
A flight simulator is a working replica of the flight deck of an aircraft mounted on
hydraulic supports that create a realistic feeling of movement.

8. • Simulation software provides a view of the simulated outside world
through the cockpit window, controls the instrument readings and
responds to commands given by the pilot.
• The main advantage of a flight simulator is that pilots can
practice how to deal with dangerous situations without putting lives
at risk or damaging expensive equipment. The instructor can set up:
• any airport
• any weather conditions
• engine, hydraulic, electrical or other ‘failures’