Recent content by user240

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    B Integrating to find surface area/volume of hemisphere

    Could you please explain/rephrase that part? I'm not sure I understand why it doesn't go to zero but the volume does (just so we're on the same page, you mean the blue part in the picture I attached, right?). Can we show this rigorously or more quantitatively? Also, why does using...
  2. U

    B Integrating to find surface area/volume of hemisphere

    To find the surface area of a hemisphere of radius ##R##, we can do so by summing up rings of height ##Rd\theta## (arc length) and radius ##r=Rcos(\theta)##. So the surface area is then ##S=\int_0^{\frac{\pi}{2}}2\pi (Rcos(\theta))Rd\theta=2\pi R^2\int_0^{\frac{\pi}{2}}cos(\theta)d\theta=2\pi...
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    Force on a Pulley: Understanding Tension and Tangents

    Could you please elaborate? I'm probably overlooking something very basic here but it's not obvious to me why the force from the rope is then given as ##2Tsin(\theta)## I'm not sure why the force happens to be ##2Tsin(\theta)## though.
  4. U

    Force on a Pulley: Understanding Tension and Tangents

    Homework Statement I'm having trouble understanding an example given in K&K's Intro to Mechanics textbook. 'A string with tension ##T## is deflected through an angle ##\theta_0## by a smooth fixed pulley. What is the force on the pulley'. I don't understand how (in the first picture) they...
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    Field along vertical axis to hemispherical shell

    Homework Statement A hemispherical shell has radius ##R## and uniform charge density ##\sigma##. FInd the electric field at a point on the symmetry axis, at position ##z## relative to the center, for any ##z## value from ##-\infty## to ##\infty##. The Attempt at a Solution Let ##\theta## be...
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