People willing to learn physics might search for something like "physics books", "physics courses", "high school physics", "guide to learning physics", and similar queries. But what I find interesting is that even the combined search volume of all of these queries much lower than that of "physics" alone.
For instance, look at this data: https://trends.google.com/trends/explore?q=physics,physics%20books,learn%20physics,physics%20for%20beginners,physics%20basics
I tried it out with almost a hundred queries (derived from Google's "searches related to [your query]" section at the bottom of the page), and still, the combined search volume would only add up to less than 20 units on Google Trends relative to 72 units for "chemistry".
I guess if there are about 500 frequently used queries (say the ones searched for more than once a week), applying the Pareto principle, the combined search volume would be no more than 30 relative units against "physics".
What do you think?