oldhomework 02-solutions

# oldhomework 02-solutions - howard(cah3459 – oldhomework...

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Unformatted text preview: howard (cah3459) – oldhomework 02 – Turner – (56705) 1 This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points Three charges are arranged as shown in the figure. x y 4 . 3 nC 4 . 4 m- . 6 nC . 99 nC- 1 . 7 m Find the magnitude of the electro- static force on the charge at the origin. The Coulomb cosnstant is 8 . 98755 × 10 9 N · m 2 / C 2 . Correct answer: 2 . 20158 nN. Explanation: Let : ( x ,y ) = (0 m , 0 m) , q =- . 6 nC , ( x 1 ,y 1 ) = (4 . 4 m , 0 m) , q 1 = 4 . 3 nC , ( x 2 ,y 2 ) = (0 m ,- 1 . 7 m) , and q 2 = 0 . 99 nC . x y q 1 x 1 q q 2 y 2 F θ The force F 10 (in the 10 direction,- ˆ ı ) be- tween charge- 6 × 10- 10 C and 4 . 3 × 10- 9 C is F 10 = + k e q q 1 x 2 1 (- ˆ ı ) = (- 8 . 98755 × 10 9 N · m 2 / C 2 ) × (- . 6 nC) (4 . 3 nC) (4 . 4 m) 2 ˆ ı = (1 . 19772 × 10- 9 N)ˆ ı. The plus sign means the force F 10 is towards the positive x-axis. The force F 20 (in the 20 direction, +ˆ ) between charge- 6 × 10- 10 C and 9 . 9 × 10- 10 C is F 20 = + k e q q 2 y 2 2 (+ˆ ) = (8 . 98755 × 10 9 N · m 2 / C 2 ) × (- . 6 nC) (0 . 99 nC) (- 1 . 7 m) 2 ˆ = (- 1 . 84727 × 10- 9 N)ˆ . The minus sign means the force F 20 is towards the negative y-axis. The magni- tude of the total force exerted on the charge- 6 × 10- 10 C is equal to F = F 2 10 + F 2 20 = (1 . 19772 × 10- 9 N) 2 + (- 1 . 84727 × 10- 9 N) 2 1 2 = 2 . 20158 × 10- 9 N = 2 . 20158 nN . 002 (part 2 of 2) 10.0 points What is the angle θ between the electrostatic force on the charge at the origin and the pos- itive x-axis? Answer in degrees as an angle between- 180 ◦ and 180 ◦ measured from the positive x-axis, with counterclockwise posi- tive. Correct answer:- 57 . 0417 ◦ . Explanation: The angle between F and the negative y- axis is θ = arctan- 1 . 84727 × 10- 9 N 1 . 19772 × 10- 9 N =- 57 . 0417 ◦ . howard (cah3459) – oldhomework 02 – Turner – (56705) 2 003 10.0 points 1.0 g of hydrogen contains 6 . 02 × 10 23 atoms, each with one electron and one proton....
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## This note was uploaded on 09/15/2010 for the course PHY 303L taught by Professor Turner during the Fall '08 term at University of Texas.

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oldhomework 02-solutions - howard(cah3459 – oldhomework...

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