Question 1:
So far in your life, you may have assumed that as you are sitting in your chair right now, you are
not accelerating. However, this picture is not quite complete! You are on the surface of the Earth,
which is rotating. Which means you are in Uniform* Circular Motion about the North-South axis
of the Earth!
(a) What is the linear acceleration of a person sitting in a chair on the equator?
(b) If you were sitting at the equator, would your mass times the gravitational acceleration of
the Earth ($mg$) be greater than, less than, or equal to the normal force exerted on you by the
chair you are sitting on? Explain.
(c) The latitude of Corvallis is 44.4°. If you were sitting in a chair in Corvallis, what would be
your linear acceleration?
(d) A classmate of yours asks you why we have ignored this acceleration for the whole first
term of physics. "Is everything we've learned a lie?" they ask. Assuming you are at the equator, use order of magnitude sensemaking arguments to assuage their fears. To do this, please answer the following prompts:
• What is the order of magnitude** of the acceleration of an object in free fall on Earth?
• What is the order of magnitude of your answer to question (c)?
• How do these orders of magnitude compare?**
• Was it an appropriate approximation to assume, as we did for all of PH201, that our acceleration was zero? Why, or why not?
