oldhw 07 - alexander (jra2623) oldhomework 07 Turner...

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alexander (jra2623) – oldhomework 07 – Turner – (92510) 1 This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 (part 1 oF 2) 10.0 points You are standing at the top oF a cli± that has a stairstep confguration. There is a vertical drop oF 6 m at your Feet, then a horizontal shelF oF 10 m , then another drop oF 4 m to the bottom oF the canyon, which has a horizontal ²oor. You kick a 0 . 31 kg rock, giving it an initial horizontal velocity that barely clears the shelF below. 10 m Δ x 10 m v 6 m 4 m What initial horizontal velocity v will be required to barely clear the edge oF the shelF below you? The acceleration oF gravity is 9 . 8 m / s 2 . Consider air Friction to be negligi- ble. Correct answer: 9 . 03696 m / s. Explanation: Let : y 1 = 6 m , y 2 = 4 m , and x = 10 m . Since all oF the vertical motion is down, we can consider down to be positive, and deal with positive gravity, vertical velocities, and distances. Thus v oy = 0, and vertical distances are defned by y = 1 2 g t 2 There is an initial horizontal velocity but a ox = 0, so horizontal distances are defned by x = v ox t Once launched, the vertical motion defnes the time to drop to the frst shelF 2 y 1 = g t 2 1 so t 1 = r 2 y 1 g Thus the horizontal distance traveled is x = v ox t 1 so v ox = x t 1 = x r g 2 y 1 = (10 m) R (9 . 8 m / s 2 ) 2 (6 m) = 9 . 03696 m / s . 002 (part 2 oF 2) 10.0 points How Far From the bottom oF the second cli± will the projectile land? Correct answer: 2 . 90994 m. Explanation: The time to drop the distance y = y 1 + y 2 to the bottom oF the cli± is t = R 2 [ y 1 + y 2 ] g , and the total horizontal distance traveled in that time is x 2 = v ox t = v ox R 2 [ y 1 + y 2 ] g = (9 . 03696 m / s) R 2 [(6 m) + (4 m)] 9 . 8 m / s 2 = 12 . 9099 m . Thus the projectile will land a distance Δ x = x 2 - x = (12 . 9099 m) - (10 m) = 2 . 90994 m ,
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alexander (jra2623) – oldhomework 07 – Turner – (92510) 2 from the bottom of the cliF. 003
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oldhw 07 - alexander (jra2623) oldhomework 07 Turner...

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