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    Lens maker's equation used correctly?

    Homework Statement An object is placed 60 cm from a thick double convex lens, with faces of radii of curvature 20 cm and 30 cm, with thickness of 2 cm, and index of refraction is 1.5. Find the position of the image...
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    Difference between two wave functions?

    Hi, I'm looking through my teacher's notes and he says that a wave function for a sinusoidal wave can be written: y = A sin (ω t – k x) or y = A sin (k x - ω t) The textbook gives it in the second form. I think that using one over the other gives the same answer but in the opposite sign. I...
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    Finding electric field via a given potential

    Homework Statement The plastic rod of the length L=1 m has a non-uniform charge density λ=cx where positive constant c =2x10^-6 [some unit]. What unit c has to have? Find the electric potential at the point on the x axis 1 m to the left from the left end of the rod. Find the electric field at...
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    Finding electric field via potential

    Homework Statement The plastic rod of the length L=1 m has a non-uniform charge density λ=cx where positive constant c =2x10^-6 [some unit]. What unit c has to have? Find the electric potential at the point on the x axis 1 m to the left from the left end of the rod. Find the electric...
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    Can you clarify this step (charge density and integrals).

    Hi, if you have the book: Physics for Scientists and Engineers 8E, Serway Jewett On page 675 (Chapter 23), Example 23.8 there is a step taken during the integration I don't understand: How do you go from "2r dr" in the numerator to d(r^2)? If there is info or link to the property of...
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    For those who have this textbook.

    Homework Statement In Physics for Scientists and Engineers Volume 1 Eighth Edition (Serway, Jewett) Number 55. in Chapter 5, I checked the answer key and would like to know why they don't consider the forces of friction in a), b), c), d), and e)? This confuses me. Thank you. Homework...
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    How to define change of angular momentum in non-isolated system?

    Homework Statement http://tycho.physics.wisc.edu/courses/phys201/fall06/Discussion/Disc14Solution.pdf [Broken] problem 38, part b) Homework Equations I final w final = I initial w initial The Attempt at a Solution I understand that the snowball is introducing a net torque and I know that...
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    Understanding about differentials?

    Homework Statement Problem 7.29: http://cas.umkc.edu/physics/wrobel/phy240/Homework%20%205.pdf Homework Equations dr= R d(theta) The Attempt at a Solution I don't understand how to get R d(theta) = dr from the last part of the question, any explanation about how it works is...
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    Solving without using differentiation?

    Homework Statement Hi all, I'm trying to understand why my second way of solving this problem doesn't work: A 3.00kg object is moving in a plane, with its x and y coordinates given by x= 5t^2–1 and y=3t^3 + 2, where x and y are in meters and t is in seconds. Find the magnitude of the net...
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    Using mass of copper in both air and liquid to find density of liquid?

    1. A piece of copper whose density is 8.93 gm/cm^3 weighs 180 gm in air and 162 gm when submerged in a certain liquid. What is the density of the liquid? 2. d = m/v 3. I wasn't sure how to compute this but I calculated the volume of the copper based on its density and air weight...
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