Physics 30 Dec 06 Diploma Exam

Inconsistencies or a major omission 1 in the response

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Unformatted text preview: a(s) and substitution, but they do not address the question • has drawn diagrams and/or sketches, if applicable, that are incorrect, inappropriate, and incomplete • has major omissions NR No response is given. Physics 30 – June 1999 iv July 16, 1999 Use the following information to answer the next question. You have the following components: an electric fan, two heating coils, several switches, and connecting wires. These components are to be used to construct a hair dryer. Schematics of Hair Dryer Components F 110 V AC Heating coil (two) Electric fan Switch (several) The design requirements for your hair dryer are that the fan is always on when the hair dryer is on and that it has two heat settings: high and low. Written Response — 15% 1. • Draw a schematic diagram of a hair dryer circuit that meets the design requirements. • Based on the circuit diagram you have drawn, analyze the operation of the hair dryer. In your response, explain how the switch settings and their locations in the circuit control the low and high heat settings. Also, explain why the hair dryer should be designed so that the fan is on whenever the hair dryer is on. Note: Marks will be awarded for the physics principles used in your response and for the effective communication of your response. Physics 30 – June 1999 v July 16, 1999 Sample Solution Switch 1 Switch 2 F Fan 110V Coil 1 Coil 2 Closing switch one, with the hair dryer plugged in, will turn on coil 1 and the fan, resulting in a low heat mode of operation. When the switches are both closed both coil 1 and coil 2, as well as the fan, are turned on resulting in the high heat mode of operation. In both modes of operation, the fan must be on and blowing air over the coils. When the coils are switched “on”, heat will be generated in the coils. It is this heat that is used to dry hair. If the fan was not on, the coil would heat up and eventually melt and/or you would probably have a hard time drying hair. Physics 30 – June 1999 vi July 16, 1999 Scoring Guide for Anaholistic Questions Major Concepts: Energy; Impulse; Vectors; Momentum. Score NR Criteria No response is given. 0 In the response, the student • identifies an area of physics that does not apply to the major concepts • uses inappropriate formulas, diagrams, and/or explanations 1 In the response, the student • attempts at least two of the major concepts or uses an appropriate method that reflects a good understanding of one of the major concepts • makes errors in the formulas, diagrams, and/or explanations, and the answer is not consistent with calculated results 2 In the response, the student • uses an appropriate method that reflects a basic understanding of three of the four major concepts or a good understanding of two of the major concepts • gives formulas and/or diagrams that are implicitly correct, however they are not applied to determine the final solution or errors in the application of equations are present but the answer is consistent with calculated results 3 In the response, the student • uses an appropriate method that reflects a basic understanding of all four of the major concepts or a good understanding of three of the major concepts • uses an appropriate method that reflects an excellent understanding of two of the major concepts and a basic understanding of one of the two remaining concepts • uses formulas and/or diagrams that may be implicit, but are applied correctly; errors in calculations and/or substitutions are present that hinder the understanding of the physics content • provides explanations that are correct but lack detail • has a major omission or inconsistency 4 In the response, the student • uses an appropriate method that reflects a good understanding of all major concepts or an excellent understanding of three of the major concepts • provides explanations that are correct and detailed • states most formulas explicitly and applies them correctly • has minor errors, omissions, or inconsistencies in calculations and/or substitutions but these do not hinder the understanding of the physics content • draws most diagrams appropriately, correctly, and completely • may have errors in units, significant digits, rounding, or graphing 5 In the response, the student • uses an appropriate method that reflects an excellent understanding of all major concepts • provides a complete description of the method used and shows a complete solution for the problem • states formulas explicitly • may make a minor error, omission, or inconsistency, but this does not hinder the understanding of the physics content • draws diagrams that are appropriate, correct, and complete • may have an error in significant digits or rounding Physics 30 – June 1999 vii Use the following information to answer the next question. Several Canadian companies are redesigning and testing bulletproof vests. One company does a test that involves firing a target rifle at a crash test dummy wearing a vest. Dummy Regular bullet mBullet = 8.00 g vBullet = 650 m/s Vest The company is testing the vests with both regular bullets and armourpiercing bullets. The armour-piercing bullet travels 1.20 times faster and has 1.20 times the mass of the regular bullet shown above. Written Response — 15% 2. • Quantitatively compare the kinetic energy of the armour-piercing bullet with t...
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