Recent content by ksinelli

  1. K

    Simple algebra/trig expression, simplifying

    Honestly I meant to write expression. Guess I was too caught up in just getting the problem out there. But thanks.
  2. K

    Simple algebra/trig expression, simplifying

    Ughhh, thank you so much. I swear I tried it in radians and it didn't come out right. I must have just made a computational error when I did it. But I just did it again and it works. I feel so stupid now, but thank you so much.
  3. K

    Simple algebra/trig expression, simplifying

    Hello, I'm trying to solve this equation. (4-4cos(∏*0.16*4)) - (4-4cos(∏*0.16*3)) It seems like it should be so easy. First I start with the left hand side (∏*0.16*4). Then I take the cosine of that, and then multiply it by 4. Then I do 4 - [answer] to get a value for the full left side...
  4. K

    What Does Infinitely Close Mean in Calculus Limits?

    This website does the same thing. They introduce a limit as some value that can never quite be reached, but can get really really close. And then by the end of the introduction, they are suddenly saying that even if it can be reached, as long as it the same number when being approached from...
  5. K

    What Does Infinitely Close Mean in Calculus Limits?

    I am trying to get a head start and learn some calculus before my class begins this fall. I'm trying to learn from Khan Academy, but I'm already confused. I thought the definition of a limit was a value that could never be reached, though could be infinitely close to being reached. Here is a...
  6. K

    When will two balls be at the same height during 1-dimensional motion?

    Homework Statement A ball is thrown upward from ground level at 25 m/s. At the same instance a 2nd ball is dropped from rest from a building 15 meters high. How high above the ground will the two balls be when they're at the same place? Homework Equations equations of uniformly...
  7. K

    Is this homework question missing information?

    I finally came back to this problem a month and a half later after giving up. I spent about two hours dissecting your posts, reading them over and over to try to fully understand the help you were giving. I did manage to solve the problem and I realized a few things. My equations were not...
  8. K

    Is this homework question missing information?

    i'm not going to lie i feel really stupid. i thought i understood this but i replied prematurely. i'm still stuck. i've got both isaac's and blaise's position as a function of time with these equations Xi = (1m/s)(Ti + 120s) - 10m Xb = (2m/s)(Tb - 120s) + 10m and as for how to...
  9. K

    Is this homework question missing information?

    ah! I remember now! Lol it's been so long since I've done this stuff, I'm actually trying to help my girlfriend with her physics homework. But I understand what you're saying and now I can explain it to her. The next step was so deceptively simple. Thanks :)
  10. K

    Is this homework question missing information?

    Here is the problem word for word: Isaaic and Blaise decide to race. They both start at the same position at the same time. Isaaic runs at 2 m/s but decides to take a 2 minute rest stop. Blaise runs at half the speed and still wins by 10 meters. How far did Blaise run? I can use only...
  11. K

    Problem understanding proportions with exponents

    i don't deny that the proportionality is true. I've substituted numbers for r and the answer comes out just as the book says. I do appreciate your help though. I've thought about this also, and it seems to be in the right direction of understanding for me, but my problem with this is that...
  12. K

    Problem understanding proportions with exponents

    I just started reading my physics book again, and one of the very first things it talks about is proportionality. I understand the concept that two things are proportional if one gets multiplied by a certain factor and the other one has to be multiplied by the same factor. For instance, if...
  13. K

    Beginner needs answers to basic questions about the speed of light

    So I've been reading Brian Greene's The Elegant Universe, and I'm not quite sure I understand general relativity. This is the way it was roughly presented in the book. Two friends are throwing a baseball back and forth at 20 m/s. However, when one of the friends begins to run away from the...
  14. K

    Which Direction Does the Force of Tension Act in a Hanging Rope?

    Hello again PF, I have some questions I have been wondering about. First of all, if you have a situation like this where a weight is hanging from a taut rope, which direction would the force of tension be in? http://img217.imageshack.us/img217/4074/tensionforce.jpg The way I understand...
  15. K

    Need someone to double check a simple problem with sig figs

    Oh ok. I understand now. In my second post I was going back to using the rule for rounding with multiplication and division problems, instead of the rule for addition and subtraction like you said. Silly me =/ Thank you much for the clarification :)
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