How to create ultra-cold temperatures (and what it tells us about the universe).
And this article (Below Absolute Zero: Negative Temperatures Explained) tells how to get below absolute zero.
Middle and High School … from a Montessori Point of View
How to create ultra-cold temperatures (and what it tells us about the universe).
And this article (Below Absolute Zero: Negative Temperatures Explained) tells how to get below absolute zero.
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.
Things get more interesting when we get away from simple circuits.
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.
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.
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.
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.
A quick program that animates scaling (dilation) of shapes by scaling the coordinates. You type in the dilation factor.
dilation.py
from visual import * #axes xmin = -10. xmax = 10. ymin = -10. ymax = 10. xaxis = curve(pos=[(xmin,0),(xmax,0)]) yaxis = curve(pos=[(0,ymin),(0,ymax)]) #tick marks tic_dx = 1.0 tic_h = .5 for i in arange(xmin,xmax+tic_dx,tic_dx): tic = curve(pos=[(i,-0.5*tic_h),(i,0.5*tic_h)]) for i in arange(ymin,ymax+tic_dx,tic_dx): tic = curve(pos=[(-0.5*tic_h,i),(0.5*tic_h,i)]) #stop scene from zooming out too far when the curve is drawn scene.autoscale = False # define curve here shape = curve(pos=[(-1,2), (5,3), (4,-1), (-1,-1)]) shape.append(pos=shape.pos[0]) shape.color = color.yellow shape.radius = 0.1 shape.visible = True #dilated shape dshape = curve(color=color.green, radius=shape.radius*0.9) for i in shape.pos: dshape.append(pos=i) #label note = label(pos=(5,-8),text="Dilation: 1.0", box=False) intext = label(pos=(5,-9),text="> x", box=False) #scaling lines l_scaling = False slines = [] for i in range(len(shape.pos)): slines.append(curve(radius=shape.radius*.5,color=color.red, pos=[shape.pos[i],shape.pos[i],shape.pos[i]])) #animation parameters animation_time = 1. #seconds animation_smootheness = 30 animation_rate = animation_smootheness / animation_time x = "" while 1: #x = raw_input("Enter Dilation: ") if scene.kb.keys: # event waiting to be processed? s = scene.kb.getkey() # get keyboard info #print s if s <> '\n': x += s intext.text = "> x "+x else: try: xfloat = float(x) note.text = "Dilation: " + x endpoints = [] dp = [] for i in shape.pos: endpoints.append(float(x) * i) dp.append((endpoints[-1]-i)/animation_smootheness) #print "endpoints: ", endpoints #print "dp: ", dp for i in range(animation_smootheness): for j in range(len(dshape.pos)): dshape.pos[j] = i*dp[j]+shape.pos[j] rate(animation_smootheness) if slines: for i in range(len(shape.pos)): slines[i].pos[1] = vector(0,0) slines[i].pos[-1] = dshape.pos[i] for i in range(len(shape.pos)): dshape.pos[i] = endpoints[i] slines[i].pos[-1] = dshape.pos[i] for i in range(len(shape.pos)-1): print shape.pos[i], "--->", dshape.pos[i] except: #print "FAIL" failed = True intext.text = "> x " x = ""
For the student who asked how do we know about black holes if we can’t see them. From NASA. Based on the paper: http://www.nasa.gov/mission_pages/chandra/destroyed-star-rains-onto-black-hole-winds-blow-it-back.html