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Unformatted text preview: HW 4: Physics 1B Spring 2010 C. M. Cooper, Teaching Assitant W. Gekelman, Professor April 22, 2010 Abstract This hw covers all of chapter 21 in the text. Topics include the introduction of electric charge, coulombs law, and the electric field. There are going to be significantly less formulars for these sections but this means a lot more derivations. This means a lot less physics and a lot more math like vector calculus in up to 3 dimensions and knowing all coordinate systems. Unique exam questions are easy to make with these sections. Its a simple as saying find the electric field of this arbitrary charge distribution: 1 equation, a lifetime to master. Its like Texas Hold ’Em. I will be playing the role of Chris Moneymaker. Please address me as such. To solve these problems you will be using the following steps: 1) draw the picture. 2) be smart about the setup and look for any symmetry or components of the field that will go to zero to make your job easier. 3) use this equation to calculate the Electric field. Z dE = E = k Z dq ( r ) r 2 (1) step 4) is the only hard part: find dq ( r ) and sub into the integral. For constant charge distributions dq ( r ) = λdr where λ = Q T ot L Remember to keep in mind how these elctrostatics problems fit into standard physics: kinematics, forces, energy, momentum. Being able to identify what the problem type is and remembering the techniques needed to solve this type is critical. In this weeks hw you have several forces/torque problems and a kinematics problem. Can you find which ones they are? 1 Question 21.33: How to build a TV Seriously, this is how TVs work. Or I should say USED to work. You crazy kids these days with the blue ray and the LECD TVs and the HD. No respect. This is a kinematics problem. we solve these using the 3 kinematics eq’s for x f ,v f , and v 2 f , and the patented 11-parameter kinematics method. This involves writing down all the kinematics variables and filling them in as we solve. 1.1 (a) What is the magnitude of the Electric field?...
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- Spring '10
- Charge, Electric charge, Fundamental physics concepts, arbitrary charge distribution