Archive for the Lesson Category

Happy Birthday, SR

Posted in Cool, Lesson, Vain Attempts at Humor on March 21, 2010 by dcbradshaw

Today in 1905, Albert Einstein published his paper, “On the Electrodynamics of Moving Bodies,” which described Special Relativity.

When asked if he thought it would be a big deal, he replied, “It all depends on how you look at it.”


The Hypothetical Sun-Earth Bridge Question

Posted in Cool, Lesson on January 2, 2010 by dcbradshaw

I do this bit in my solar system lectures:

Imagine a bridge that stretched from the earth to the sun, and you could drive a vehicle on this bridge.  If you started driving at 70 miles per hour, nonstop — and when I say “nonstop” I mean without stopping to eat, or to go to the bathroom, or to refuel the car — if you drove nonstop at 70 miles per hour, how long would it take you to get to the sun?

Fifth grade flashbacks!  It’s WORD PROBLEMS!

This is actually pretty easy to work through, but the result is so surprising that you may think you got the answer wrong.

Start with the distance from Earth to Sun.  The number everyone seems to know off the top of their heads is 93 million miles, and though that’s rounded a little bit (and also not metric…), we’ll go with it.

Actually, let’s break it down a little more: how long would it take to go 1 million miles at 70mph nonstop?

Good ol’ d = rt, don’t fail me now!  1,000,000 miles divided by 70 mph equals roughly 14,286 hours, divided by 24 hours in a day, equals 595 days.

That’s a long time to drive nonstop.

So, if 595 days equals 1 (million miles), 595 days times 93  (million miles) equals the driving days to the sun: 55,335 days.

55,335 (days) divided by 365 (days per year) equals 151.6 years.

151 years.

If you drove nonstop from the earth to the sun at 70 miles per hour, it would take you about 150 years of driving to get there.

Starcrossed #2

Posted in Comic, Lesson with tags , , on July 4, 2009 by dcbradshaw


Chicken bone, ball syringe, it’s all the same.

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