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    Limit of a function

    a = 15. So that means I just have to learn that by heart? Isn't there sort of a formal proof to test that? On the other hand, how do you know there's a factor in common between the top and bottom knowing that numerator and denominator are zero? Thank you for your answer.
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    Matrices and infinite solutions

    Homework Statement Find h so that: -8x + -7y = 7 16x + hy = 14 has infinitely many solutions (solve this exercise with matrices). Homework Equations - The Attempt at a Solution I converted the system to matrix form, but when I try to convert it to echelon form, I get the...
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    Limit of a function

    Homework Statement Does lim x-> -2 (3x2+ax+a+3)/(x2+x-2) exist? If so, find the limit. Homework Equations - The Attempt at a Solution I've tried factorizing the denominator to (x+2)(x-1), but then I don't know how to proceed on the exercise. I have seen that the limit exists...
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    How to measure copper sulfate specific heat

    Homework Statement I was wondering, how can i measure the specific heat capacity of a solution? Not the exercise, just doing an experimental work to measure it. Homework Equations q=mct The Attempt at a Solution I'm lost.
  5. I

    Wave pulses velocity

    Bump, really need help!
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    Wave pulses velocity

    Homework Statement In the picture. Homework Equations I guess λ=cv? I'm not sure on this one. The Attempt at a Solution I don't know how the velocity and the displacement are related in this exercise. However, i do recall the graphs of displacement, velocity and acceleration in SMH.
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    Magnetic field caused by a current-carrying wire

    So i just sort of "expand" the magnetic field lines until it reaches the point P? And the direction would be upwards if i draw a "tangent" to the magnetic field (which is in a curve) at that point.
  8. I

    Magnetic field caused by a current-carrying wire

    You can use that "thumb-rule" with the right hand? As the current is going into the paper, the magnetic field would be in a clock-wise direction. On the other hand, the lines would be circles in which the magnetic field is in a clock-wise direction. The "right hand rule" is used because the...
  9. I

    Magnetic field caused by a current-carrying wire

    Homework Statement In the picture. Homework Equations Right/left hand rule? The Attempt at a Solution I have tried applying the right hand rule to this situation, but they only give me the current and nothing else, so i can't determine the direction of the magnetic field in the point P.
  10. I

    Mass between two springs

    Hey, thanks for repplying! Well i've tried to mount it vertically.. but it doesn't work. Or maybe i'm doing it wrong. Gravity makes the mass go down, but not up.
  11. I

    Mass between two springs

    Hello! My second time here, and this forum has really been helpful. I got a question: How could i do an experiment to study the SHM of a mass between two springs? I've tried doing it, but the mass can't complete one cycle, and friction is always a problem. Is there a way to reduce it...
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    Lifting Books - Potential Energy

    Homework Statement A student has six books, all of them with a 4cm thickness and a weight of 30N. ¿What would be the minimum work to put the books in one pile, if the six books are in a table? Weight: 30N Thickness: 4cm. Gravity: 9.81ms-2 Homework Equations Ep=mgh Ec=(mv2)/2...
  13. I

    Lifting books - Potential Energy

    I need help on this proble: A student has six books, all of them with a 4cm thickness and a weight of 30N. ¿What would be the minimum work to put the books in one pile, if the six books are in a table?
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    Measuring gravitational force of the Earth

    Alright.. seems to complicated, thanks anyways! I've heard also of an experiment with a spring, how does it work?
  15. I

    Measuring gravitational force of the Earth

    And how could i measure g with the Atwood machine? The equation should be: a = g(m-m2)/(m+m2)
  16. I

    Measuring gravitational force of the Earth

    Well my teacher said no pendulums.. That's the problem lol.
  17. I

    Momentum-related exercise

    Damn what an idiot! Thank you!!!!!
  18. I

    Momentum-related exercise

    Gotcha, it does, thank you!!!! Last question: Why should the velocity of the water change?
  19. I

    Momentum-related exercise

    The mass would then double, and therefore, velocity would double also? Giving a value of 4F. Is this the correct way to solve the problem?
  20. I

    Momentum-related exercise

    Anyone got any idea? My HW is for Saturday. :S
  21. I

    Momentum-related exercise

    Gotcha, but i only get 2F as an answer..
  22. I

    Momentum-related exercise

    Need help on this problem: 10. A fireman is holding a hosepipe so that water leaves the pipe horizontally. The hosepipe has a constant cross-sectional area. The magnitude of the force that the fireman exerts to hold the hosepipe stationary is F. The volume of water delivered by the hose per...
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    Measuring gravitational force of the Earth

    Alright thanks. I'll try that and tell you if it works! Just in case, how does a free fall apparatus work?
  24. I

    Measuring gravitational force of the Earth

    Yeah, i was planning on dropping the ball at height 0.7m,0.8m,0.9m and 1m. That way the height is easily calculated, but the main problem is the time taken...
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    Measuring gravitational force of the Earth

    Yeah, i wanted to measure g (Sorry if you're getting confused, English isn't my main language). Do you know about the "free-fall" apparatus?
  26. I

    Measuring gravitational force of the Earth

    Alright calm down lol. I was just asking. So you mean that i should record when the object falsl and then stop it when it touches the ground?
  27. I

    Measuring gravitational force of the Earth

    Right. But do you have any idea on how to do it with home-made materials? Or not too expensive? Or could you give me the link of that Mythbusters video? THANKS!
  28. I

    Measuring gravitational force of the Earth

    So you're saying that i should use v2=2gs instead of s=gt2/2? And how could i measure the final velocity?
  29. I

    Measuring gravitational force of the Earth

    Well, i'm gonna do it with falling objects, i need something that can record time with accuracy. And with scales.. You're measuring force directly. I need to relate the height of fall and the time taken.
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