HW 2-solutions

# HW 2-solutions - morris(gmm643 – HW 2 – Coker –(56625...

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Unformatted text preview: morris (gmm643) – HW 2 – Coker – (56625) 1 This print-out should have 14 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. In class we did not cover the part of Ch. 3 dealing with vector products, and vector products will not be covered on this home- work or on Quiz 1. Vector products will be in- troduced in later chapters as they are needed for the concepts of work and torque. 001 10.0 points A hiker makes three straight-line walks A 18 km at 249 ◦ B 24 km at 32 ◦ C 27 km at 126 ◦ in random directions and lengths starting at position (41 km , 41 km) , listed below and shown below in the plot. A B C Scale: 10 km = Figure: Drawn to ok. Which vector will return the hiker to the starting point? All angles are measured in a counter-clockwise direction from the positive x-axis. 1. bardbl vector D bardbl = 29 . 8432 km , θ d = 129 . 242 ◦ 2. bardbl vector D bardbl = 48 . 5917 km , θ d = 262 . 812 ◦ 3. bardbl vector D bardbl = 13 . 4911 km , θ d = 287 . 152 ◦ 4. bardbl vector D bardbl = 17 . 8657 km , θ d = 276 . 323 ◦ cor- rect 5. bardbl vector D bardbl = 37 . 383 km , θ d = 353 . 36 ◦ 6. bardbl vector D bardbl = 43 . 2297 km , θ d = 73 . 2102 ◦ 7. bardbl vector D bardbl = 66 . 4533 km , θ d = 90 . 7368 ◦ 8. bardbl vector D bardbl = 64 . 1863 km , θ d = 192 . 747 ◦ 9. bardbl vector D bardbl = 38 . 1275 km , θ d = 77 . 7664 ◦ 10. bardbl vector D bardbl = 60 . 3069 km , θ d = 64 . 3143 ◦ Explanation: Δ a x = (18 km) cos249 ◦ = − 6 . 45059 km , Δ a y = (18 km) sin249 ◦ = − 16 . 8045 km , Δ b x = (24 km) cos32 ◦ = 20 . 3532 km , Δ b y = (24 km) sin32 ◦ = 12 . 7181 km , Δ c x = (27 km) cos126 ◦ = − 15 . 8702 km , Δ c y = (27 km) sin126 ◦ = 21 . 8434 km , A B θ d C D Scale: 10 km = Δ x = Δ a x + Δ b x + Δ c x morris (gmm643) – HW 2 – Coker – (56625) 2 = − 6 . 45059 km + (20 . 3532 km) + ( − 15 . 8702 km) Δ y = Δ a y + Δ b y + Δ c y = − 16 . 8045 km + (12 . 7181 km) + (21 . 8434 km) The resultant is D = radicalBig (Δ x ) 2 + (Δ y ) 2 = radicalBig (39 . 0323 km) 2 + (58 . 7571 km) 2 θ D = arctan vextendsingle vextendsingle vextendsingle vextendsingle 58 . 7571 km − (41 km) 39 . 0323 km − (41 km) vextendsingle vextendsingle vextendsingle vextendsingle = 276 . 323 ◦ ....
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## This note was uploaded on 11/17/2010 for the course PHY 56630 taught by Professor Coker during the Spring '10 term at University of Texas.

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HW 2-solutions - morris(gmm643 – HW 2 – Coker –(56625...

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