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Kinematics without definite values

  • Thread starter JJ91284
  • Start date
  • #1
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I've got a homework packet that I've been working on that's due tomorrow afternoon. I was planning on visiting the physics tutoring center today on campus, but everything is shut down because of the 21" of snow that we got last night.

I have 3 problems that I've been staring at for the last hour or more and I just don't know how to proceed. Normally I have no issues what so ever when data is given. These problems don't have definite numbers so I'm struggling on how to even proceed.

Any guidance on how to get going would be appreciated

Normally I use these 4 equations and I just manipulate the equations and they work great.

X=X0+V0t+.5at2
V=V0+at
V2=V02+2aΔX
S=d/t

I'm attaching 3 links so you can see my physics problems. One last question I'd like to ask just to make sure I answered another problem correctly in my packet. When a problem asks when is its velocity greatest. Do you always go with the the highest positive number, or do you factor in a negative value as well. I know speed doesn't matter which direction your going. Velocity sign (+ or -) on the other hand indicates which direction. So if you have steeper declining slope vs a lower inclining slope on a position vs time graph, would the steeper declining slope have a greater velocity?

P1
http://img20.imageshack.us/img20/7853/001vtt.jpg [Broken]

P2
http://img543.imageshack.us/img543/9262/2001v.jpg [Broken]

P3
http://img80.imageshack.us/img80/1522/3001hs.jpg [Broken]
 
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Answers and Replies

  • #2
gneill
Mentor
20,793
2,773
You proceed by using the same formulas. The answers will simply be in terms of the given information (h, d, t, etc.).

Presumably the idea is to get you thinking in terms of manipulating the mathematical formulae to a final, simplified result formula before numbers are plugged in. Eventually you will appreciate that this avoids a lot of rounding and truncation errors creeping into lengthy strings of manipulations.

Why don't you take the first problem (the falling flower pot) and give us your thoughts on how to proceed. Make an attempt and we can help.
 

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