Author: Lensyl Urbano

Vpython on the Web with Glowscript

Using glowscript.org, we can now put vpython programs online. Here’s a first shot of the coil program:

http://www.glowscript.org/#/user/lurbano/folder/Private/program/magnet-coil.py

Moving the magnet through a wire coil creates an electric current in the wire.
Moving the magnet through a wire coil creates an electric current in the wire.

Some changes to the standard vpython language must be used and there are some limitations, but it seems to work.

The Joy of Math

Regardless, if learning is to be as efficient and deep as possible, it’s essential that it be done freely. That means giving children a voice in which activities to participate, for how long, and also the level of mastery they want to achieve. (“This is the biggest clash with traditional curriculum development,” Droujkova notes.)
— Vangelova (2014): 5-Year-Olds Can Learn Calculus

This article provides a lot of evidence to support the notion that the conceptual aspects of calculus and other “higher level” forms of math should be taught at all age levels, not just at the end of high school or in college.

The presentation below elaborates:

The Flint Water Crisis

What happened:

  • Flint switches from Detroit’s water system to the Flint River to save money,
  • E. coli bacteria show up in water (E.coli can make you sick) so the water system adds chlorine to kill the bacteria,
  • Trichloromethane shows up in the water (trichloromethane is a carcinogen)
  • Water from the Flint River is more corrosive compared to Detroit’s because it has higher levels of chlorine ions (Cl–),
  • Chlorine dissolves lead from old water pipes — the lead goes into solution in the water (lead causes issues with mental development in kids, among other things),

References

Detailed article from Mashable: The poisoning of a city

A timeline from Michigan Radio: TIMELINE: Here’s how the Flint water crisis unfolded

An excellent, detailed program from Reveal: Do not drink: The water crisis in Flint, Michigan. The second part in particular is a good summary of the science issues.

A NPR summary from September 29th, 2015: High Lead Levels In Michigan Kids After City Switches Water Source

Circuit Basics

Studying voltage and current in circuits can start with two laws of conservation.

Note: Some of the links are dead, but this MIT Opencourse pdf has a detailed explanation. And Kahn Academy has some videos on the current laws as well.

  • KCL: Current flow into a node must equal the flow out of the node. (A node is a point on the wire connecting components in a circuit–usually a junction).
(KCL: Kirchoff's Current Law) Current flowing into any point on a circuit is equal to the current flowing out of it, A simple circuit with a voltage source (like a battery) and a resistor.
(KCL: Kirchoff’s Current Law) Current flowing into any point on a circuit is equal to the current flowing out of it, A simple circuit with a voltage source (like a battery) and a resistor.

  • KVC: The sum of all the voltage differences in a closed loop is zero.

KVL: The voltage difference across the battery (9 Volts) plus the voltage difference across the resistor (-9 Volts) is equal to zero.
KVL: The voltage difference across the battery (9 Volts) plus the voltage difference across the resistor (-9 Volts) is equal to zero.

Things get more interesting when we get away from simple circuits.

Current flow into a node (10 A) equals the flow out of the node (7 A + 3 A).
Current flow into a node (10 A) equals the flow out of the node (7 A + 3 A).

Note that the convention for drawing diagrams is that the current move from positive (+) to negative (-) terminals in a battery. This is opposite the actual flow of electrons in a typical wired circuit because the current is a measure of the movement of negatively charged electrons, but is used for historical reasons.

Based on the MIT OpenCourseWare Introduction to Electrical Engineering and Computer Science I Circuits 6.01SC Introduction to Electrical Engineering and Computer Science Spring 2011.

Glossary of Plant Description

From: The vPlants Project. vPlants: A Virtual Herbarium of the Chicago Region. http://www.vplants.org
From: The vPlants Project. vPlants: A Virtual Herbarium of the Chicago Region. http://www.vplants.org

The vPlants Project. vPlants: A Virtual Herbarium of the Chicago Region. http://www.vplants.org is a wonderfully comprehesive collection of pictures with plant descriptions: plant form; leaf shapes; stem and leaf patterns; flower shapes; and more.

Melting Ice Caps and Flooding in Miami

The Siege of Miami: A detailed report that looks at the increasing frequency of flooding in Miami, because of sea-level-rise. The reporter interviews a number of scientists and engineers who are not terribly optimistic about the long-term (50+ years) future of many Floridian cities because of the melting ice-caps in Greenland and Antarctica.

Flooded street during a "King Tide" in Miami Beach, Florida. Image from NOAA.
Flooded street during a “King Tide” in Miami Beach, Florida. Image from NOAA.

New Particles

Physicists in Europe Find Tantalizing Hints of a Mysterious New Particle: This new particle, if confirmed to exist (the data is not conclusive) seems to go beyond the Standard Model of physics that we know and love.

The last sub-atomic particle discovered was the Higgs boson, which is shown in the graph below.

Finding the Higgs Boson "The strongest evidence for this new particle comes from analysis of events containing two photons. The smooth dotted line traces the measured background from known processes. The solid line traces a statistical fit to the signal plus background. The new particle appears as the excess around 126.5 GeV. The full analysis concludes that the probability of such a peak is three chances in a million. " from ATLAS.
Finding the Higgs Boson “The strongest evidence for this new particle comes from analysis of events containing two photons. The smooth dotted line traces the measured background from known processes. The solid line traces a statistical fit to the signal plus background. The new particle appears as the excess around 126.5 GeV. The full analysis concludes that the probability of such a peak is three chances in a million. ” from ATLAS.