Electricity and Magnetism
Free Response Question #3 Solutions - AP Physics C 1998 Released Exam
This Free Response Question includes the following concepts: Magnetic Forces, Current, Motional Emf, Newton’s 2nd Law, Magnetic Flux, Electric Potential Difference, Current, Resistance, Electric Power, Terminal Velocity and using the integral to find the speed as a function of time when the acceleration is not constant.
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Link: AP Physics C 1998 Released Exam
The problem is on pages 168 - 169 of this pdf.
Their solution is on pages 214 - 215 of this pdf.
Please enjoy my solutions as well.
0:30 A general description of the problem
2:09 Part (a) The Right Hand Rule!
4:18 Part (a) Breaking the Force of Gravity in to its Components
6:46 Part (a) Summing the forces in the Parallel Direction
8:40 Part (b) Deriving Motional emf
11:36 Part (b) Solving for Current
12:07 Part (c) Solving for Electric Power
12:56 Part (d) Reviewing the limits of the speed of the bar
14:06 Part (d) Summing the forces in the Parallel Direction (It’s a little bit different this time)
15:43 Part (d) Substituting in for the Current
16:37 Part (d) Integration!
18:42 Part (d) Substituting in the Limits
21:07 Part (d) Reflecting on how Part (d) was graded
22:33 Part (d) Checking our solution using the limits
23:56 Part (e) Determining what happens to the Equivalent Resistance
25:00 Part (e) Determining what happens to the Terminal Speed