By Mary Morel
Both proportional and proportionate mean properly related in size, degree or other measurable way, i.e. in proportion.
However, proportional has a specific mathematical meaning that proportionate doesn’t. For instance, you could say:
The field strength is proportional to the transmitted power.
The concentration of the final solution is proportional to the amount of solute.
The force on the pinion is proportional to the length of the lever and the applied force.
You could not use proportionate in any of these examples.
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