Ch6-HW3-solutions - louey (cal2859) Ch6-HW3 florin (56930)...

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Unformatted text preview: louey (cal2859) Ch6-HW3 florin (56930) 1 This print-out should have 15 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 A two-dimensional force vector F = F x + F y moves a particle to a new location that is vectorr = r x + r y from where it was originally located. If F x = 1 N, F y = 1 N, r x = 1 m, and r y = 2 m, what is the work done on the particle by the force? Correct answer: 1 J. Explanation: The work is given by W = vector F vectorr = F x r x + F y r y = (1 N) (1 m) + ( 1 N) (2 m) = 1 J . 002 (part 2 of 2) 10.0 points Find the angle between vector F and vectorr . Correct answer: 108 . 435 . Explanation: Since W = vector F vectorr = vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectorr | cos = cos 1 W vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectorr | . vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle = radicalBig F 2 x + F 2 y = radicalBig (1 N) 2 + ( 1 N) 2 = 1 . 41421 N and | vectorr | = radicalBig r 2 x + r 2 y = radicalbig 1 m 2 + 2 m 2 = 2 . 23607 m , so = cos 1 bracketleftbigg 1 J (1 . 41421 N) (2 . 23607 m) bracketrightbigg = 108 . 435 . 003 (part 1 of 6) 4.0 points A lithium nucleus has mass 5 . 1 10 27 kg. If its speed is 0 . 988 c (that is, v/c = 0 . 988), what is the particle energy? Use c = 3 10 8 m / s. Correct answer: 2 . 97176 10 9 J. Explanation: The particle energy is just the total energy, given by E = m c 2 . So we have E = 1 radicalBigg 1 parenleftbigg v c parenrightbigg 2 m c 2 = 1 radicalbig 1 . 988 2 (5 . 1 10 27 kg) c 2 = 2 . 97176 10 9 J . 004 (part 2 of 6) 4.0 points What is the rest energy? Correct answer: 4 . 59 10 10 J. Explanation: The rest energy is just E rest = m c 2 = (5 . 1 10 27 kg) c 2 = 4 . 59 10 10 J . 005 (part 3 of 6) 4.0 points What is the kinetic energy? Correct answer: 2 . 51276 10 9 J. Explanation: The kinetic energy is given by KE = E E rest = 2 . 97176 10 9 J 4 . 59 10 10 J = 2 . 51276 10 9 J ....
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This note was uploaded on 03/20/2012 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

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Ch6-HW3-solutions - louey (cal2859) Ch6-HW3 florin (56930)...

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