# 8 - roofner(bar784 – Homework 8 – Weathers –(17104 1...

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Unformatted text preview: roofner (bar784) – Homework 8 – 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 . Let: F x = 6 N, F y = − 5 N, s x = 5 m, and s y = 2 m. Find the work done by the force on the particle. Correct answer: 20 J. Explanation: The work is given by W = vector F · vectors = F x s x + F y s y = (6 N) (5 m) + ( − 5 N) (2 m) = 20 J . 002 (part 2 of 2) 10.0 points Find the angle between vector F and vectors . Correct answer: 61 . 607 ◦ . Explanation: Since W = vector F · vectors = vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectors | cos θ . The first and the third sides can be solved for θ to give θ = cos − 1 W vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle | vectors | . First of all vextendsingle vextendsingle vextendsingle vector F vextendsingle vextendsingle vextendsingle = radicalBig F 2 x + F 2 y = radicalBig (6 N) 2 + ( − 5 N) 2 = 7 . 81025 N and | vectors | = radicalBig s 2 x + s 2 y = radicalbig 5 m 2 + 2 m 2 = 5 . 38516 m . Thus θ = cos − 1 bracketleftbigg 20 J (7 . 81025 N) (5 . 38516 m) bracketrightbigg = 61 . 607 ◦ . 003 10.0 points A shopper in a supermarket pushes a cart with a force of 37 . 7 N directed at an angle of 25 . 7 ◦ downward from the horizontal. Find the work done by the shopper as she moves down a 48 . 5 m length of aisle....
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8 - roofner(bar784 – Homework 8 – Weathers –(17104 1...

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