## Recommended Posts

44 minutes ago, novi said:

Assuming standard physics word problem rules and constant forces, and not showing my work because I don't want to type in that many equations.  And assuming I remember how significant digits work:

1.  6.563 x 10^6 J

2.  8.576 x 10^3 N

3.  6.43 x 10^5 W

Yes, I got an A in AP Physics.  Why do you ask?

Excellent! Did you solve the problem by finding acceleration from the velocities, or did you use the Work-Energy Theorem?

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FWIW, I have often given astrophysical situations in problems where the values invoked are way outside most people's experience.

For instance, I'll be asking the students next quarter to compare the heat from Earth's accretion to that from its differentiation, and later (after they have read a useful reference) to the heat of radioactive decay over the 4.55 Gyr since accretion.  The problems are easy (the first is just the gravitational binding energy of a uniform sphere of Earth's mass and radius; for the second I give them a core density and radius, and tell them the rest is in the mantle and give them that density) but unfamiliar.

Later we'll do the conservation of angular momentum for the Earth-Moon system.

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2 hours ago, Rails said:

If you're going to drive 200+ mph, are you going to bother trying to stop at lights?

Dude, I don't stop at lights now.

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22 minutes ago, Cancer said:

FWIW, I have often given astrophysical situations in problems where the values invoked are way outside most people's experience.

And yet students come up with answers that are blatantly wrong anyway.  Orbital velocities greater than c.  Negative volume.  And why can't they check the units?!  Work is not measured in meters per second!

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21 minutes ago, Old Man said:

And why can't they check the units?!  Work is not measured in meters per second!

This. This right here.

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48 minutes ago, Cancer said:

FWIW, I have often given astrophysical situations in problems where the values invoked are way outside most people's experience.

I recently gave my students a conservation of momentum problem involving a U-238 atom that underwent alpha decay. Boy, were the results all over the place.

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1 hour ago, Old Man said:

Dude, I don't stop at lights now.

I wouldn't either, but the I'd plow into the 3 cars in front of me who decided to.

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42 minutes ago, Pariah said:

I recently gave my students a conservation of momentum problem involving a U-238 atom that underwent alpha decay. Boy, were the results all over the place.

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44 minutes ago, Pariah said:

I recently gave my students a conservation of momentum problem involving a U-238 atom that underwent alpha decay. Boy, were the results all over the place.

Make it a beta-decay with an electron and a neutrino, and have them deduce which way the neutrino went from the post-decay velocity vectors of nucleus and electron.

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5 hours ago, Cancer said:

Make it a beta-decay with an electron and a neutrino, and have them deduce which way the neutrino went from the post-decay velocity vectors of nucleus and electron.

The number is 47.

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9 hours ago, Pariah said:

In my defense, I am a first-year Physics teacher. I'm used to dealing with things on a much smaller scale. That, and I was writing the problem as the tardy bell was ringing this morning.

Let's see if any of my students catch the problem as well as you all did.

Gold stars for everyone!

Yes!  My first gold star!

Come to think of it...my very first star!

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8 hours ago, Pariah said:

I recently gave my students a conservation of momentum problem involving a U-238 atom that underwent alpha decay. Boy, were the results all over the place.

What about a problem involving Illudium PU-36 that modulates space when exploding?

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11 hours ago, Pariah said:

In my defense, I am a first-year Physics teacher. I'm used to dealing with things on a much smaller scale. That, and I was writing the problem as the tardy bell was ringing this morning.

Let's see if any of my students catch the problem as well as you all did.

Gold stars for everyone!

My first gold star for physics and I didn't do any work! Bonus!

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13 hours ago, Pariah said:

Excellent! Did you solve the problem by finding acceleration from the velocities, or did you use the Work-Energy Theorem?

Um, Work-Energy Theorem?  It's been... a while since I had a physics class, so I did a quick Wikipedia visit to make sure I had my formulas correct.  And while I was all set to work out the acceleration, I then noticed the page mentioning that work is also equal to delta-Kinetic energy.  Seemed like a much more straightforward and accurate approach.

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2 hours ago, novi said:

Um, Work-Energy Theorem?  It's been... a while since I had a physics class, so I did a quick Wikipedia visit to make sure I had my formulas correct.  And while I was all set to work out the acceleration, I then noticed the page mentioning that work is also equal to delta-Kinetic energy.  Seemed like a much more straightforward and accurate approach.

Teacher's pet!

Ugh. Triggered.

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One of these times, the answer will be 47.

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13 hours ago, Starlord said:

What about a problem involving Illudium PU-36 that modulates space when exploding?

You can do that, but general relativistic spacetime lattice calculations are generally not found in undergraduate-level material, let alone high school.

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Quote

Oh, and on the homework ... remember how I talked about satanic questions?  Problem 8 is a satanic question.

See you Wednesday.  Have a good weekend!

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, and problem 666 is about puppies!

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Just think of the experiments we could run if we could get a reliable source for antipuppies!  "PUPPY-ANTIPUPPY COLLISIONS AT 0.99c".  Now there's some research!

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*calls PETA to Cancer's lab.*

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*observes Cancer crashing PETA into each other at 0.99c*

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2 hours ago, Old Man said:

*observes Cancer crashing PETA into each other at 0.99c*

Tell me when the Kickstarter goes live.

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Quote

A scientist just scored honors for a musical adaptation of his research on Friday.

Pramodh Senarath Yapa, a physicist currently pursuing his doctorate at the University of Alberta in Edmonton, Canada, has been named the 2018 winner of the "Dance Your Ph.D." contest.

The competition, sponsored by the American Association for the Advancement of Science (AAAS) and Science magazine, invites doctoral students and Ph.D. recipients to translate their research into an interpretive dance. The winner takes home \$1000.

It took Senarath Yapa six weeks to choreograph and write the songs for "Superconductivity: The Musical!" — a three-act swing dance depicting the social lives of electrons. The video is based on his master's thesis, which he completed while pursuing his degree at the University of Victoria in Canada.

The 11-minute sing-songy rendition is far less paralyzing than the jargony title of Senarath Yapa's thesis alone: "Non-Local Electrodynamics of Superconducting Wires: Implications for Flux Noise and Inductance."

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