Design Engineering Theory Topics - Home Page




1 Calculating Area


Area of a square and a circle

2 Mechanical advantage


Mechanical advantage

3 Pulley, belt drive and gear ratio


Pulley ratios

  • Below are videos of how to calculate gear ratios and speed calculation for a pair of gears and a compound gear set.

  • The formula above applies to all drive systems. For pulleys, you would use the diameter instead of number of teeth.
  • Chain and sprocket calculations will be the same as gear calculations.
  • One thing to note, in gear drive systems, the gears will spin in opposite directions as they move through the gears.

4 Graphs


Mean, Mode and Median


5 Percentages

Percentage increase or decrease


6 Ohm's law


Series resistor calculations

Parallel resistor calculations


Series resistor voltage calculations

Parallel resistor voltage calculations