solution1_pdf - white (rw22679) – Hw01 – Ross –...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: white (rw22679) – Hw01 – Ross – (10219) 1 This print-out should have 16 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points You have 2 . 8 kg of water. One mole of water has a mass of 17 . 9 g / mol and each molecule of water contains 10 electrons since water is H 2 O. What is the total electron charge contained in this volume of water? Correct answer: − 1 . 50722 × 10 8 C. Explanation: Let : N A = 6 . 02214 × 10 23 molec / mol , q e = − 1 . 6 × 10 − 19 C / electron , m = 2 . 8 kg , M = 17 . 9 g / mol = 0 . 0179 kg / mol , and Z = 10 electrons / molec . The mass is proportional to the number of molecules, so for m grams in n molecules and M grams in N A molecules, m M = n N A n = m M N A Since 10 electrons are in each molecule of water, then the total number of electrons n e in the coin is n e = Z n = Z m M N A and the total charge q for the n e electrons is q = n e q e = Z m N A q e M = (10 electrons / molec) 2 . 8 kg . 0179 kg / mol × ( 6 . 02214 × 10 23 molec / mol ) × ( − 1 . 6 × 10 − 19 C / electron ) = − 1 . 50722 × 10 8 C . 002 (part 1 of 2) 10.0 points Three charges are arranged in a triangle as shown. + − + . 193 m . 888 m 6 . 17 nC − 2 . 8 nC 2 . 8 nC y x What is the net electrostatic force on the charge at the origin? The Coulomb constant is 8 . 98755 × 10 9 N · m 2 / C 2 . Correct answer: 4 . 17305 × 10 − 6 N. Explanation: Let : q 1 = 6 . 17 nC = 6 . 17 × 10 − 9 C , q 2 = 2 . 8 nC = 2 . 8 × 10 − 9 C , q 3 = − 2 . 8 nC = − 2 . 8 × 10 − 9 C , r 1 , 2 = 0 . 888 m , r 1 , 3 = 0 . 193 m , and k C = 8 . 98755 × 10 9 N · m 2 / C 2 . F 1 , 2 F 1 , 3 F θ The repulsive force F 1 , 2 = k C q 1 q 2 r 2 1 , 2 = 8 . 98755 × 10 9 N · m 2 / C 2 × ( 6 . 17 × 10 − 9 C )( 2 . 8 × 10 − 9 C ) (0 . 888 m) 2 = 1 . 96906 × 10 − 7 N white (rw22679) – Hw01 – Ross – (10219) 2 acts along the negative x-axis, and the attrac- tive force F 1 , 3 = k C q 1 | q 3 | r 2 1 , 3 = 8 . 98755 × 10 9 N · m 2 / C 2 × ( 6 . 17 × 10 − 9 C )( − 2 . 8 × 10 − 9 C ) (0 . 193 m) 2 = − 4 . 1684 × 10 − 6 N acts along the negative y-axis. Thus F net = bracketleftbig (1 . 96906 × 10 − 7 N) 2 +( − 4 . 1684 × 10 − 6 N) 2 bracketrightbig 1 / 2 = 4 . 17305 × 10 − 6 N . 003 (part 2 of 2) 10.0 points What is the direction of this force (as an angle between − 180 ◦ and 180 ◦ measured from the positive x-axis, with counterclockwise posi- tive)? Correct answer: − 92 . 7045 ◦ ....
View Full Document

This note was uploaded on 12/01/2010 for the course PHYSICS 21900 taught by Professor Rhoads during the Spring '10 term at IUPUI.

Page1 / 7

solution1_pdf - white (rw22679) – Hw01 – Ross –...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online