Pi Day!

Today we practiced using compasses (will use in earthquake triangulation) and celebrated Pi day by finding the meaning of pi; it is the number of times a circle's diameter will go about its circumference. A circle's radius will go around its circumference 6.28 times, or 2 pi. Radians are the measurement of angles equal to one unit of radius about a circle's circumference.

We continued discussion of relevant topics from Japan's earthquake and Tsunami today after learning more regarding "S" and "P" waves; specifically:
S waves move through the crust at about 3000 m/s and P waves move at about 5000 m/s
(Primary and Secondary waves)
S waves do most damage, and are associated with rolling motions that cause tall buildings to rock and fall. Shorter buildings or buildings that are mounted into bedrock don't have the same scale of problems.
A location some distance away from the earthquake will experience two waves; first, the primary (P) wave, and later, the secondary (S) wave. The farther the site is from the earthquake source, the greater the time delay between P and S wave arrival.
Practice: New Madrid (240km away) has an earthquake. Find time for each wave to arrive, and find the delay between P and S waves.
P: 240,000m / 5000 m/s = 48 seconds
Now find S using the same method and the slower (3000 m/s) speed...
S: 240,000m / 3000 m/s = 80 seconds

Delay: 80s - 48s = 32 seconds.

Homework: Find the delay between P&S waves for a distance you choose. This can be any number, but if you make it realistic it may mean more to you; try out a distance you know if you can. To convert miles to km, multiply miles by 1.61.

AND
Homework due Wednesday (even if you're supposed to take the PLAN, make sure you've done it in case it's postponed...)
Read p. 354-361. P. 357 has one problem; do it. also, P. 361#1-9