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Can you pass 8th grade science?


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Not bad... I would have liked to have done better. I don't remember learning most of that in 8th Grade. I think I learned some of it then and most of it since. Edited by doojable
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I'm surprised I did as well as a C. Science was always hard for me. At the time, I was glad the science curriculum was so sparse as I didn't like taking the courses. The current curriculums are so much better. By 5th grade, my kids have learned all I learned in school and more.

Suda

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I can't figure out how to copy the image with the grade here, but much to my surprise, I got a B+ (88). I thought I missed a lot more questions than I did.

Now, if that were a math quiz instead of a science quiz, I think I'd be too embarrassed to post my score.

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I knew that comets were composed of [xxxxxxxxx], but I did not know that the [xxx] was "left over from the formation of our solar system." Good thing I didn't need to know that part.... it was a given.

Good test, GT. I barely passed.

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I couldn't copy it over here either! I did pretty good. There would be something very wrong if the science teacher didn't get an A you kmow!

A reasonable test except that the earth's gravitational constant is not 10 m/sec (squared) it is 9.8 on average with the understanding that the earth's gravitational field is not uniform over the entire surface. Gravity anomalies have been mapped extensively from space and vary widely as much as +/- .2 m/sec (squared). I assume they used 10 m/sec (squared) for ease of calculation which is about as scientifically honest as calling pi = 3.1

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A reasonable test except that the earth's gravitational constant is not 10 m/sec (squared) it is 9.8 on average with the understanding that the earth's gravitational field is not uniform over the entire surface. Gravity anomalies have been mapped extensively from space and vary widely as much as +/- .2 m/sec (squared). I assume they used 10 m/sec (squared) for ease of calculation which is about as scientifically honest as calling pi = 3.1

if it weren't an eighth grade test, I'd say they were trying to catch those over thinking the problem. i.e. How do we know if the object stopped when it hit the water or not? If it stopped the velocity is zero if the g=9.8, zero if g = 10, zero if g=156,748.

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if it weren't an eighth grade test, I'd say they were trying to catch those over thinking the problem. i.e. How do we know if the object stopped when it hit the water or not? If it stopped the velocity is zero if the g=9.8, zero if g = 10, zero if g=156,748.

I think - given the choices - you can presume final velocity is at time of impact which is 100 m/s**2 (using their flawed GC). Assuming the stone was not pumice the final velocity would be zero since the stone would rapidly decelerate on water impact and then slowly come to zero as it hit the sea floor. The rate of descent between surface and sea floor will vary with salinity, etc (i.e. density) of the water itself.

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A reasonable test except that the earth's gravitational constant is not 10 m/sec (squared) it is 9.8 on average with the understanding that the earth's gravitational field is not uniform over the entire surface. Gravity anomalies have been mapped extensively from space and vary widely as much as +/- .2 m/sec (squared). I assume they used 10 m/sec (squared) for ease of calculation which is about as scientifically honest as calling pi = 3.1

Even more interesting is that gravity appears about 1/2 percent stronger at the poles than the equator. That's because of the sum of two effects, the outward centrifugal force at the equator canceling a portion of the gravitational pull, and the same centrifugal force bulging the earth out at the equator, placing the surface of the earth farther from the center of gravity. A simplistic explaination, I know, but it will do.

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RumRunner said:

A reasonable test except that the earth's gravitational constant is not 10 m/sec (squared) it is 9.8 on average with the understanding that the earth's gravitational field is not uniform over the entire surface. Gravity anomalies have been mapped extensively from space and vary widely as much as +/- .2 m/sec (squared). I assume they used 10 m/sec (squared) for ease of calculation which is about as scientifically honest as calling pi = 3.1

I'm pretty sure you're right about ease of calculation. Usually they don't permit calculators during tests like this. I noticed that all the answers were combinations of 1 and 0 with various decimal values in there. I think they were more interested in finding out if the student knew how to use the formula.

If that was a real test, I'd like to see the rest of it to see more of what was in the curriculum. There were only 26 questions so I'm sure there had to be more the students were supposed to know.

And it is very nice to see you here. I've kind of missed your font from time to time.

Edited by krysilis
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I'm pretty sure you're right about ease of calculation. Usually they don't permit calculators during tests like this. I noticed that all the answers were combinations of 1 and 0 with various decimal values in there. I think they were more interested in finding out if the student knew how to use the formula.

And it is very nice to see you here. I've kind of missed your font from time to time.

Why thank you Krys.

I do get annoyed however at "ease of calculation" for students. As I have always taught; the science is in the numbers. Eighth graders, at least in my kids school district, have already had one year of algebra and, hence, should be able to handle 9.8 vs 10. It's a simple formula based on what is called the two body gravitation problem. And comparing the gravitational attraction of a "stone" as compared to the earth the smaller body's attraction becomes negligible and simplifies the calculation even more.

I used pi as an example because the state of Indiana once passed a vote in the legislature to define pi = 3.1 for ease of calculation (interesting to think one could presume to legislate the value of pi). Would you drive across a suspension bridge which someone used pe = 3.1 for the calculation of the curve fit for the suspension cable lengths? Better yet, and more to the point, would you boost or reenter on a shuttle for which someone used a uniform GC error of 2 percent on the ballistic calculation? Might have a few problems on orbit insertion and reentry.

Nice to see you too.

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I like rumrunners points about over simplifying ... and I'll bring up Al Gore's global warming. Not considering how many variables there are and how complicated determining all those really is, can lead to some simple conclusions that are simply unfounded.

It does seem humorous or dangerous that the value of pi can be legislated. If pi=3.1, it can surely be proved that 2+2=5 :o

And it seems the bigger part of the inaccuracy besides the truncated g and not saying "the final velocity just before impact", is not considering air resistance. Understanding that would help clear up that urban legend about the penny dropped from the empire state building embedding itself 6 inches into the concrete, because of the incredible speed it reaches. I think terminal velocity is when air resistance =g?

Of course the questions are greatly abbreviated, but it would be educational to see just how many assumptions are made even in something so seemingly simple.

so we would really need to consider:

the shape of the stone,and smoothness, making it really impossible to be completely accurate

the density

g at that location

the downdraft from the helicopter that dropped the stone

???

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It does seem humorous or dangerous that the value of pi can be legislated. If pi=3.1, it can surely be proved that 2+2=5 :o

To your point Rhino... 0.99999 (to infinity) can indeed be proven to equal 1.0. Case in point:

X = 0.9999999 (etc)

10X = 9.9999999 (etc)

Subtract 1X yields 9X = 9.0

Divide by 9 yields

1X = 1.0

Hence 1X = 1.0 and also = 0.9999999 (etc)

So while the algebra is flawless it fails to take into account the "law of density of natural numbers"

Much like politics - I can give you a "flawless" argument - and by simple omission of one or more boundary conditions I can prove anything I want...

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