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  1. C

    Dielectrics help

    just kidding
  2. C

    Nonuniform Semicircle of Charge

    No, it doesn't have to be zero. Imagine that most of the charge is located on one side, or if on one side it's more to the top and the other has more to the side; the x-component wouldn't be 0.
  3. C

    Simple Projectile Motion

    You have an equation already; are you asking how to solve for t? It's a quadratic equation... EDIT: That equation doesn't have any real solutions; are you sure that 142.5 is the initial velocity in the y-direction?
  4. C

    Mass on an incline plane

    Are you sure about the sign for the acceleration? Which direction is defined as positive or negative?
  5. C

    Calculate Acceleration Given V0 and X

    Are you sure you calculated the initial velocities correctly?
  6. C

    Help with Coulombs Law

    The magnitude of the vector is always positive; you have the angle to account for the direction. However, the actual vector can be going in the negative direction.
  7. C

    Help with Coulombs Law

    You posted Coulomb's law for the electric force. Draw a diagram and use vectors to represent the each force on the charge at the origin, then you should be able to get the magnitude of the resultant vector.
  8. C

    Four Charges

    What have you tried so far?
  9. C

    Calculate Acceleration Given V0 and X

    You have to go a little bit outside of plugging values into the kinematic equations. Hint: The maximum distance the ball goes is 90m. EDIT: Sid beat me to it.
  10. C

    Help with Coulombs Law

    You should have the two perpendicular force vectors starting at the origin; they form a right triangle... If you have the two legs of a right triangle, you should be fine figuring out the rest of the parts of the triangle.
  11. C

    Help with Coulombs Law

    You want to find the magnitude, and the direction (angle)
  12. C

    Help with Coulombs Law

    For part a, you used Coulomb's law to find the force exerted by each charge on the charge at the origin. Have you paid attention to their directions? If you draw them as vectors, how would the resultant vector look? And for electric field, you want to use the other charge as the Q you're using.
  13. C

    Help with Coulombs Law

    Could you post your work?
  14. C

    Help with Coulombs Law

    Have you attempted to solve it?
  15. C

    Help with Coulombs Law

    Yes, the n stands for nano, 10^{-9}
  16. C

    Help with Coulombs Law

    You're essentially finding the force exerted by a charge on an infinitesimally small positive charge, which happens to be placed at the origin. electric field = kQ/r^2
  17. C

    Integration Homework Help

    Yup, that doesn't sound right. Be careful when you're picking u for a u-substitution...
  18. C

    Find the net amount of charged contained in a cube

    flux = EA = Q/ε You're given the electric field at both surfaces, so you can find E. A is just the area of the two squares. Then ε is constant, just solve for Q.
  19. C

    HELP with Charges

    Are you using UTexas Quest? If so, does it give you a value for k? The rounding difference might make your answer a bit off.
  20. C

    Help with Coulombs Law

    If it's counterclockwise from the negative x-axis, start from the left x-axis then go down.