Modeling Practices

Physics is all about creating the most accurate models of our complex world. Incorporate these features to clearly measure and explain phenomenon you measure. 

DATA COLLECTION

• Repeat runs if time allows.
• Consistently apply your testing method.
• Usually, keep all variables the same besides your manipulated/independent variable.
• Collect at least 10 data points. 
• Make sure your independent variable range is at least a factor of 10 (if your lowest mass is 1kg, measure up to 10 kg). 

GRAPHING

• Label your graph, typically using the format Dependent variable vs independent variable. EG. Pasta Bridge Strength vs Bridge Design.
• Place your measured/dependent variable on the vertical axis. Independent/controlled variable on the horizontal axis. 
• Label your axis using the format variable (units). E.g. Force (Newtons). 
• Include a line of best fit and an equation. 
• Start your graph at (0,0). 

MATH MODELS (EQUATIONS)

Using a linear y = mx + b model as an example:

• Replace y and x with the variable names (for our pasta experiment, y was pasta strength and x was bridge design).
• Include units for the slope and vertical intercept. 

Pasta Bridge Strength = 20 (pennies/noodle) * bridge design + (2 pennies) 

Describe your relationship with a slope sentence and vertical intercept.

For every 1 unit increase in manipulated variable, the dependent variable increased/decreased by slope coefficient (dependent variable units)

For every 1 noodle increase in bridge design, the pasta bridge strength increased by 20 pennies. 

When the bridge had no noodles, the pasta could hold 2 pennies. Since a bridge that doesn't exist cannon hold any pennies, and since the vertical intercept is less than 5% the maximum penny value we measured, we believe the vertical intercept can be ignored.