This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: hernandez (ejh742) – oldhomework 07 – Turner – (58120) 1 This printout should have 16 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Four vectors, each of magnitude 83 m, lie along the sides of a parallelogram as shown in the figure. The angle between vector A and B is 67 ◦ . A 8 3 m C 83 m B 83 m D 8 3 m 67 ◦ What is the magnitude of the vector sum of the four vectors? Correct answer: 276 . 85 m. Explanation: Let : α = 67 ◦ and ℓ = 83 m . The vectors are vector B = vector C = ℓ ˆ ı and vector A = vector D = ( ℓ cos α ) ˆ ı + ( ℓ sin α ) ˆ , so vector A + vector B + vector C + vector D = 2 ℓ (1 + cos α )ˆ ı + 2 ℓ sin α ˆ = 2 (83 m) (1 + cos 67 ◦ ) ˆ ı + 2 (83 m) sin 67 ◦ ˆ = (230 . 861 m) ˆ ı + (152 . 804 m) ˆ , and R = radicalBig (230 . 861 m) 2 + (152 . 804 m) 2 = 276 . 85 m . Alternate Solution: Rotate the figure clockwise by 1 2 α . The resultant vector must lie along the horizontal line connecting the tails of vectors A and B and the heads of vectors C and D . The four components along this line are ℓ cos parenleftBig α 2 parenrightBig , so R = 4 ℓ cos parenleftBig α 2 parenrightBig = 4 (83 m) cos (33 . 5 ◦ ) = 276 . 85 m . 002 10.0 points A novice golfer on the green takes three strokes to sink the ball. The successive dis placements are 4 . 4 m to the north, 2 . 5 m northeast, and 8 . 6 m 18 ◦ west of south. Start ing at the same initial point, an expert (lucky) golfer could make the hole in a single displace ment. What is the magnitude of this single dis placement? Correct answer: 2 . 19934 m. Explanation: Take the sum of these three displacements: d = d 1 + d 2 + d 3 = d x ˆ ı + d y ˆ where d x = d 2 cos 45 ◦ − d 3 sin30 ◦ d y = d 1 + d 2 sin45 ◦ − d 3 cos 30 ◦ so, the magnitude of d is:  d  = radicalBig d 2 x + d 2 y 003 (part 1 of 2) 10.0 points A submarine dives 135.0 m at an angle of 16.0 ◦ below the horizontal. What is the horizontal component of the submarine’s displacement? Correct answer: 129 . 77 m. Explanation: hernandez (ejh742) – oldhomework 07 – Turner – (58120) 2 Let : d = 135 . 0 m and θ = − 16 ....
View
Full
Document
This note was uploaded on 06/14/2011 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas.
 Spring '08
 Turner
 Physics, Work

Click to edit the document details