PH101 HW 2D Motion

# PH101 HW 2D Motion - This print-out should have 15...

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Unformatted text preview: 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 cat climbs 20 m directly up a tree. What is the horizontal component of the cat’s displacement? Correct answer: 0 m. Explanation: Let : d = 20 m and θ = 90 ◦ . 20m Δ x = (20 m)(cos 90 ◦ ) = 0 m . 002 (part 2 of 2) 10.0 points What is the vertical component of the cat’s displacement? Correct answer: 20 m. Explanation: Δ y = d sin θ = (20 m) sin 90 ◦ = 20 m . 003 (part 1 of 2) 10.0 points A descent vehicle landing on the moon has a vertical velocity toward the surface of the moon of 23 . 7 m / s. At the same time, it has a horizontal velocity of 55 m / s. At what speed does the vehicle move along its descent path? Correct answer: 59 . 889 m / s. Explanation: Let : v v = 23 . 7 m / s , and v h = 55 m / s . v h v v v θ The speeds act at right angles to each other, so v = v 2 h + v 2 v = (55 m / s) 2 + (23 . 7 m / s) 2 = 59 . 889 m / s . 004 (part 2 of 2) 10.0 points At what angle with the vertical is its path? Correct answer: 66 . 6883 ◦ . Explanation: v h is the side opposite and v v is the side adjacent to the angle, so tan θ = v h v v θ = arctan v h v v = arctan 55 m / s 23 . 7 m / s = 66 . 6883 ◦ . 005 10.0 points Three vectors A , B , and C have the following x and y components: A x = 2 . 3, A y =- 1 . 8; B x =- 3 . 5, B y = 4 . 3; C x = 2 . 3, C y = 3 . 6. What is the magnitude of A + B + C ? Correct answer: 6 . 19839. Explanation: Given : A = (2 . 3 ,- 1 . 8) , B = (- 3 . 5 , 4 . 3) , and C = (2 . 3 , 3 . 6) . Let D = A + B + C . The x component o f D is D x = A x + B x + C x = 2 . 3+(- 3 . 5)+2 . 3 = 1 . 1 and the y component of D is D y = A...
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## This note was uploaded on 10/03/2010 for the course PH 101 taught by Professor Jones,s during the Spring '08 term at Alabama.

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PH101 HW 2D Motion - This print-out should have 15...

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