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# hw8b - khounvivongsy(sk27799 – Homework 08b – Weathers...

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khounvivongsy (sk27799) – Homework 08b – Weathers – (17104) 1 This print-out should have 11 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 force vector F = F x ˆ ı + F y ˆ acts on a particle that undergoes a displacement of vectors = s x ˆ ı + s y ˆ where F x = 10 N, F y = 4 N, s x = 4 m, and s y = 2 m. Find the work done by the force on the particle. Correct answer: 32 J. Explanation: The work is given by W = vector F · vectors = F x s x + F y s y = (10 N) (4 m) + ( 4 N) (2 m) = 32 J . 002 (part 2 of 2) 10.0 points Find the angle between vector F and vectors . Correct answer: 48 . 3665 . Explanation: Since W = vector F · vectors = vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectors | cos θ θ = cos 1 W vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectors | . vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle = radicalBig F 2 x + F 2 y = radicalBig (10 N) 2 + ( 4 N) 2 = 10 . 7703 N and | vectors | = radicalBig s 2 x + s 2 y = radicalbig 4 m 2 + 2 m 2 = 4 . 47214 m , so θ = cos 1 bracketleftbigg 32 J (10 . 7703 N) (4 . 47214 m) bracketrightbigg = 48 . 3665 . 003 10.0 points A shopper in a supermarket pushes a cart with a force of 32 . 7 N directed at an angle of 23 . 9 downward from the horizontal. Find the work done by the shopper as she moves down a 49 . 4 m length of aisle. Correct answer: 1 . 47687 kJ. Explanation: Given : F shopper = 32 . 7 N , θ = 23 . 9 , and d = 49 . 4 m .

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