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Mechanics Free Response Question #3 Solutions - AP Physics C 1998 Released Exam
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This Free Response Question includes the following concepts: Free Body Diagrams (or Force Diagrams), Static and Kinetic Friction, Tension, Force Normal, Force of Gravity, Newton’s Second Law (many times), a Multiple Bock System and a Pulley.
AP® is a registered trademark of the College Board, which was not involved in the production of, and does not endorse, this product. Enjoy an EDpuzzle Lesson for this video. Link: AP Physics C 1998 Released Exam The problem is on pages 159 - 161 of this pdf. Their solution is on pages 191 - 193 of this pdf. Please enjoy my solutions as well. Content Times: 0:22 Describing the Problem 1:24 Part (a) Drawing the Free Body Diagrams of the Whole System 1:58 Part (a) Forces of Gravity (or Weights) 2:22 Part (a) Tension Forces 2:53 Part (a) Normal Forces 4:06 Part (a) Friction Force(s) 4:56 Answering Part (a i) through (a v) 6:02 Part (b) 1st Net Force Equation 7:22 Part (b) 2nd Net Force Equation 8:20 Part (b) 3rd Net Force Equation 10:35 Part (c) Describing this part of the Problem 12:19 Part (c) The only Net Force Equation for Part (c) 14:37 Part (d) 15:29 Part (d i) 16:27 Part (d ii) |
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I made a video called, “8 General Suggestions for the Free Response Questions of any AP Physics Exam.” And then I proceeded to make video solutions to the 3 Free Response Questions of the 1998 AP Physics C Mechanics Exam and I learned a valuable lesson. I should have given 9 suggestions. I should have added a 9th suggestion: “Read Carefully.”
I find it quite funny that I didn’t read carefully enough because (1) for years it is something I berated my students about and (2) it is something I did not do on the third free response question. You see, I didn’t answer part (a) completely. I missed the small word “magnitude”. I simply drew the forces in the Free Body Diagrams, however, I didn’t explicitly solve for the Magnitudes of the Forces. All the magnitudes of the forces are in my solutions because I had to find each one to solve the rest of the problem; however, I didn’t quite answer part (a) correctly. I did put the complete solution in my solutions. :)
I don’t know how the AP graders would grade my solution because all the physics is there, just not in the right places; however, I do feel they would not have given my solution full credit. So, please learn from my mistake and read the questions carefully. Don’t have to eat humble pie, like me.
I find it quite funny that I didn’t read carefully enough because (1) for years it is something I berated my students about and (2) it is something I did not do on the third free response question. You see, I didn’t answer part (a) completely. I missed the small word “magnitude”. I simply drew the forces in the Free Body Diagrams, however, I didn’t explicitly solve for the Magnitudes of the Forces. All the magnitudes of the forces are in my solutions because I had to find each one to solve the rest of the problem; however, I didn’t quite answer part (a) correctly. I did put the complete solution in my solutions. :)
I don’t know how the AP graders would grade my solution because all the physics is there, just not in the right places; however, I do feel they would not have given my solution full credit. So, please learn from my mistake and read the questions carefully. Don’t have to eat humble pie, like me.
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