Comparison Style Questions - PhysPrimer

Examples of comparison style questions (which show up a lot in physics courses), which are generally of the form: If I change X by a certain factor, what factor will Y change by.

0:00 Introduction (general form of comparison questions)
1:33 General method for solving
2:44 Example 1 (how changing circle radius affects area)
4:23 Why can we arbitrarily pick starting values?
5:56 Example 2 (how changing pendulum length affects period)
8:45 Example 3 (how changing star distance and luminosity affects brightness)
11:35 Example 4 (how changing temp and amount of ideal gas affects pressure)
15:08 Review of general method
16:03 Try it yourself examples (solutions at end of description)


Opening Image Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (STScI), Image Processing: Alyssa Pagan (STScI)
https://science.nasa.gov/missions/jam...

Solutions to "Try it yourself" examples (and I do recommend trying these yourself BEFORE looking at solution):

1) If same force applied to object 10x more massive, the acceleration,

a = F_net / m

will be 0.1x original value

2) If you have a spring with half the stiffness but with double the stretch, the potential energy stored will be doubled.