tMB post of the week @lionjim edition

[laKavosiey-st lion]

I always see a bunch of threads and posts here about how terrible the schools in Chicago are, and I myself have begun to question the quality of the education students are receiving here.

So in my efforts to be the best teacher I can be, I decided that I need to do everything I can to sure my students have access to the quality and rigor of education that will give them an opportunity to be successful in life.

One evaluation tool I’m going to use is to compare their aptitude with that of a message board full of people who all make $400k+/yr. To accurately assess, I will give you a pretty simple problem to solve. If I see the high percentage of correct answers I expect to see from the MB, I will know that my students are being shorted in their educations.

I believe in student-led classrooms, so we did an activity in my physics class where students came up with their own problems that they would then use to teach the class themselves. This is a pretty simple problem that most student groups solved in under 2 minutes:

“A motorcycle is traveling at 10m/s and then decelerates at -1.3m/s^2. What is the distance it travels before stopping?”

I’m sure most of you can solve this pretty quickly in their heads, but I will be able to tell if you cheat and use Google.

Thanks for helping me become a better teacher to the children of Chicago.

 

[laKavosiey-st lion]

So Jim how far?

 

[LionJim]

Acceleration a

Velocity v(t)
v(t) = a×t + v(0) = 0 (stops) at t = -v(0) ÷ a = -10 ÷ (-1.3) = 7.692037692 s.

Distance traveled s(t)
s(t) = (a/2)×t^2 + v(0)×t + s(0)
= (a/2)×t^2 + v(0)×t +0
=(-1.3/2)×t^2 + 10×t = 38.46153846 meters.

 

[PSU73]

Let me dumb down the results. I got 13.1. May have messed up since I was writing it out on my hand with an ink pen.

 

[Midnighter]

Acceleration a

Velocity v(t)
v(t) = a×t + v(0) = 0 (stops) at t = -v(0) ÷ a = -10 ÷ (-1.3) = 7.692037692 s.

Distance traveled s(t)
s(t) = (a/2)×t^2 + v(0)×t + s(0)
= (a/2)×t^2 + v(0)×t +0
=(-1.3/2)×t^2 + 10×t = 38.46153846 meters.

@laKavosiey-st lion :

 

[BobPSU92]

I don’t get it.

 

[Woodpecker]

Hmmm, the driver continues at 10 m/s so I gotta wonder if the motorcycle's deceleration remains constant as it bounces along the road.

 

[BobPSU92]

Acceleration a

Velocity v(t)
v(t) = a×t + v(0) = 0 (stops) at t = -v(0) ÷ a = -10 ÷ (-1.3) = 7.692037692 s.

Distance traveled s(t)
s(t) = (a/2)×t^2 + v(0)×t + s(0)
= (a/2)×t^2 + v(0)×t +0
=(-1.3/2)×t^2 + 10×t = 38.46153846 meters.

What a bunch of cockamamie nonsense. I give you credit for creativity, though.

 

[Bison13]

Decelerating at -1.3 m/s^2, so its speeding up?

Doing related rates in non ap calc class this week so we've had some interesting questions.

 

[LionJim]

Decelerating at -1.3 m/s^2, so its speeding up?

Ah. Excellent trick. Joke's on me. After all these years Rick shows his subtle side. Who knew?

 

[LionJim]

It's like asking how many of each animal Moses brought onto the ark.

 

[step.eng69]

I always see a bunch of threads and posts here about how terrible the schools in Chicago are, and I myself have begun to question the quality of the education students are receiving here.

So in my efforts to be the best teacher I can be, I decided that I need to do everything I can to sure my students have access to the quality and rigor of education that will give them an opportunity to be successful in life.

One evaluation tool I’m going to use is to compare their aptitude with that of a message board full of people who all make $400k+/yr. To accurately assess, I will give you a pretty simple problem to solve. If I see the high percentage of correct answers I expect to see from the MB, I will know that my students are being shorted in their educations.

I believe in student-led classrooms, so we did an activity in my physics class where students came up with their own problems that they would then use to teach the class themselves. This is a pretty simple problem that most student groups solved in under 2 minutes:

“A motorcycle is traveling at 10m/s and then decelerates at -1.3m/s^2. What is the distance it travels before stopping?”

I’m sure most of you can solve this pretty quickly in their heads, but I will be able to tell if you cheat and use Google.

Thanks for helping me become a better teacher to the children of Chicago.

Speak in another language....like the imperial system

 

[Woodpecker]

It's like asking how many of each animal Moses brought onto the ark.

Forget it; he's rollin'

 

[Mr. Potter]

I would have given the same answer as LionJim but he wasn't sitting in front of me.

Shalom

 

[PSUFTG]

Acceleration a

Velocity v(t)
v(t) = a×t + v(0) = 0 (stops) at t = -v(0) ÷ a = -10 ÷ (-1.3) = 7.692037692 s.

Distance traveled s(t)
s(t) = (a/2)×t^2 + v(0)×t + s(0)
= (a/2)×t^2 + v(0)×t +0
=(-1.3/2)×t^2 + 10×t = 38.46153846 meters.

x

 

[LionJim]

x

It’s exactly the same thing. Nice thinking. Not sure why you deleted it, as it’s very cool. This is how a physicist would think of it. It’s also an indication of my personal limitations as a mathematician, I’m not Uber creative.

 

[PSUFTG]

It’s exactly the same thing. Nice thinking. Not sure why you deleted it, as it’s very cool. This is how a physicist would think of it. It’s also an indication of my personal limitations as a mathematician, I’m not Uber creative.

Yeah, I was going to write something along the lines of why this type of question is a good "IQ test" type question - because it can actually be solved, real quick, by "figuring it"
The "figuring" going along the lines of:
A) With a constant rate of deceleration, one can figure out real quick how long it takes (from 10 to 0 in 7.69 seconds - just 10/1.3) So that is really simple, 7.69 sec
B) The average rate, given a straight line from 10 to 0, is 5 m/s... is really simple
So it is just 7.69 seconds X 5m/sec

So someone with zero higher order math skills - just the ability to multiply and divide, can "figure" the answer, lickity-split, in just a couple seconds.

Obviously, to be able to solve for any number of less basic situations - such as variable rates of speed decline due to some force - one would have to know (have been taught) relatively higher levels of math (ie: calculus, perhaps),

I always liked these types of "problems", in general, as an instructor, because it does evaluate the ability to ponder out a simple solution - independent of the solvers specific training or education - just the ability for the brain to "figure **** out".