## How Does the Value of an Inverse Cosine Function Change When the Unit of its Argument Changes?

How does the value of $\cos^{-1} \left ( 0.1 \, \textrm{cm} \right )$ differ from $\cos^{-1} \left ( 0.1 \, \textrm{m} \right )$? This is an interesting question, especially because the question of units in trigonometric and inverse trigonometric functions is rarely discussed in mathematics textbooks. It is discussed in physics textbooks, so you may … Read more

## Why do Airplanes Fly?

In many physics textbooks, the explanation for lift on a flying airplane is that the top of a plane’s wing is longer than the bottom, and so air must travel faster across the top than the bottom, and therefore the pressure is lower above the wing than below. (This difference in pressure associated with different … Read more