Kaiser442
Contributor
Yeah - throwing in unnecessary information (like how deep the object is... has NO effect on the bouyancy of an incompressible object!) is the best way to throw people off.
Can't Do This Scuba Math....A test for you
- Thread starter scubajoh44
- Start date
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There is a lot to be said for the metric system! Killed my instructors that I work in both!
well i see i am not the only one having problems with this test, i have completed all of my othere requirments but i can not pass the physics test for nothing as i am completly ignorant at the math part, this physics test is kicking my *** some how i must learn the math stuff!!!!!!!!!!
OP
Well, if physics TEACHERS have problems.....don't feel too bad yourself! I think 99% of the population couldn't do these. I had NO clue two weeks ago.
Blackwood
Contributor
scubajoh44:
Hell, even the people who wrote the questions apparently don't understand them.
1) They say instruct you to disregard the minimal positive buoyancy of the added lead, and then they give you an example in which the positive buoyancy of the added lead is not minimal.
2) They don't give you enough information to solve the problem. You must make assumptions such as the object is neutrally buoyant and non-dynamic (up or down) to solve the problem. And even then, the answer will not be Air Volume = X. It will be Air Volume > X (greater than 10.75 cuft from the looks of things, but I didn't solve the problem).
Oh, come on guys, it's a simple problem. It's stuff I expect my advanced students to handle.
The problem with writing "simple" questions is that often the "simple" answer is wrong.Walter:
The way question #1 is written (that is, disregarding the 3# positive buoyancy of the object in average density salt water, and assuming the lead is weighed on the surface)... the correct answer is (to one significant decimal place) 54.4 pounds of lead.
If the buoyancy discrepancy is taken into account, then you'd need 57.4 pounds of lead.
But... I'll bet dollars to donuts the person who wrote the "simple" question wants a "simple" answer of 50 pounds. Wrong, but simple
Rick
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