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Unformatted text preview: Physics for Scientists and Engineers, 6e Chapter 7 Energy and Energy Transfer The gravitational force exerted by the Sun on the Earth holds the Earth in an orbit around the Sun. Let us assume that the orbit is perfectly circular. The work done by this gravitational force during a short time interval in which the Earth moves through a displacement in its orbital path is 1 2 3 4 25% 25% 25% 25% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 1. zero 2. positive 3. negative 4. impossible to determine The force does no work on the Earth because the force is pointed toward the center of the circle and is therefore perpendicular to the direction of the displacement. Which of the following statements is true about the relationship between A B and ( A ) ( B )? 1 2 3 4 25% 25% 25% 25% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 1. A . B = [( A ) . ( B )] 2. If A B = AB cos , then ( A ) ( B ) = AB cos ( + 180) 3. Both (a) and (b) are true. 4. Neither (a) nor (b) is true. Answer (1) is incorrect because the scalar product ( A ) ( B ) is equal to A B . Answer (2) is incorrect because AB cos ( + 180) gives the negative of the correct value. Which of the following statements is true about the relationship between the dot product of two vectors...
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This note was uploaded on 01/19/2010 for the course PHYS 200 taught by Professor Davies during the Spring '08 term at Roger Williams.
 Spring '08
 Davies
 Energy, Force, Work

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