exam1_sol-1 - PHY2049 Spring 2006 Exam 1 Solutions Prof...

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PHY2049 Spring 2006 Exam 1 Solutions Prof. Darin Acosta Prof. Greg Stewart February 13, 2006 Exam 1 Solutions 1. A particle with charge 3μC is placed at the origin, an identical particle, with the same charge, is placed 2m from the origin on the x axis, and a third identical particle, with the same charge, is placed 2m from the origin on the y axis. The magnitude of the force on the particle at the origin is: a. 2.9 × 10 -2 N b. 1.4 × 10 -2 N c. 2.0 × 10 -2 N d. 4.0 × 10 -2 N e. 8.1 × 10 -2 N As all charges are the same, the force is repulsive between the first and second particle (directed in direction), and first and third particle (directed in ˆ x ˆ y direction). The magnitude of the force between each pair of particles is the same since the distances are the same: () ( ) 2 2 2 96 12 12 22 9 10 3 10 C / 2 m 0.02 N qq q Fk k dd == = ×× = But when the forces from each pair of particles are added vectorially, the overall magnitude is 12 2 0.029 N F = 2. An electron and a proton are separated by a distance of d =5.3 ×10 -11 m. What is the magnitude of the acceleration of the electron immediately after both particles are released from rest? a. 9.0×10 22 m/s 2 b. 8.2×10 -8 m/s 2 c. 4.8×10 12 m/s 2 d. 5.6×10 41 m/s 2 e. 1.0×10 13 m/s 2 The proton has an equal and opposite electric charge to the electron. So the magnitude of the force between them is: 2 19 98 2 11 8 22 2 31 1.6 10 C 9 10 8.2 10 N 5.3 10 m 91 0 m / s 9.11 10 kg e F F a m × = × × × = × × 1
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PHY2049 Spring 2006 Exam 1 Solutions 3. Arrangement of point charges on a square lattice, length of each side=d. '+' marks the four corners of the square. The point marked by 'O' is in the center of the square. The positive charge at each corner is shown in parentheses after the '+' marking the corners; 'n' is some integer.
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This note was uploaded on 04/12/2008 for the course PHY 2049 taught by Professor Any during the Fall '08 term at University of Florida.

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exam1_sol-1 - PHY2049 Spring 2006 Exam 1 Solutions Prof...

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