Recent content by jna

  1. J

    B Why is the height of a liquid not affected by the radius of a U-Shaped tube

    Maybe, I guess @AmirWG should comment, and I do not mean to diminish your effort answering what you believe was the OP's confusion. All I can say with absolute certainty is that the highlighted wording in the textbook is irritatingly confusing to me.
  2. J

    B Why is the height of a liquid not affected by the radius of a U-Shaped tube

    I think that the OP's intended question has not been answered by any of the above (albeit informative) responses. I think his/her confusion stems from the inaccurate wording in the textbook. The text claims that the height is not affected by the diameter of the tube. Clearly, that is incorrect...
  3. J

    Determine the friction force in a stacked block scenario

    So, as the solution for F_fr I am getting 80/3 (approx. 26.7) N. Unfortunately, that does not match any of the values in the multiple choice: {A. 99 N, B. 12 N, C. 63 N, D. 75 N}. I am ok with that as long as I know this result is correct - are you getting the same? Thanks for all your help again.
  4. J

    Determine the friction force in a stacked block scenario

    Let me try (forces acting to the left +, to the right -): For Block A: (net force A) = (acting force F) - (friction/drag from from block B) For Block B: (net force B) = (friction force from A) where (friction force from A) = - (friction/drag from from block B) --- so: m_A * a_A = F - F_fr m_B...
  5. J

    Determine the friction force in a stacked block scenario

    Yes, I agree that 75N/30kg was not the right thing to solve this (original attempt). That's why I posted the revised attempt (#3) which does not go into determining the acceleration of the block A at all, just considers forces.
  6. J

    Determine the friction force in a stacked block scenario

    I see. Re the first part, fF=63N causing an acceleration of 2.625 m/s^2 was still fine to me because I only assumed a relative reduction of acceleration of B by 0.5 m/s^2 (the 0.5 m/s^2 is specified as "to the right relative to block A). I do understand that the force 63N makes B accelerate to...
  7. J

    Determine the friction force in a stacked block scenario

    It would be helpful if you could point out where I went wrong with the 63N reasoning. I am just unsure what to do with the two hints.
  8. J

    Determine the friction force in a stacked block scenario

    Ah sorry i actually meant to say the same (misread your question). But can you please help me correct my answer?
  9. J

    Determine the friction force in a stacked block scenario

    Hmm, yes I am pretty sure I broke something. So a more careful but still blurry look: Block A exerts force through friction on block B in the direction <--. Obviously, that force exceeded the opposing max friction force of B on A pointing -->, since block B is sliding and accelerating 0.5 m/s^2...
  10. J

    Determine the friction force in a stacked block scenario

    Homework Statement Assume that block A which has a mass of 30 kg is being pushed to the left with a force of 75 N along a frictionless surface. What is the friction force of block A on block B if the block B has a mass of 24 kg and is accelerating at 0.50 m/s2 to the right relative to the block...
  11. J

    What Causes the Sinusoidal Waviness in UARS Orbital Altitudes?

    I am trying to imagine the action: suppose there is a drag force acting exactly at the perigee. This results in lowering the altitude of every point of the orbit except the perigee, making both \dot e and \dot a negative. I can't explain to myself how any amount of drag applied at perigee could...
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