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Unformatted text preview: schroeder (cs39963) Resource 4: Two Dimensional Motion  Projectile and Circular Moton balasubra This printout should have 29 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A golfer takes two putts to get his ball into the hole once he is on the green. The first putt displaces the ball 4 . 8 m east, and the second 4 . 5 m south. What displacement would have been needed to get the ball into the hole on the first putt? Correct answer: 6 . 57951 m. Explanation: Let : x = 4 . 8 m and y = 4 . 5 m . 4 . 80 m 4 . 50 m R E S The east direction and the south direction define legs of a right triangle. The resultant is the hypotenuse, so the displacement is R = radicalBig ( x ) 2 + ( y ) 2 = radicalBig (4 . 8 m) 2 + ( 4 . 5 m) 2 = 6 . 57951 m . 002 (part 2 of 2) 10.0 points What is the direction (in degrees S of E)? Correct answer: 43 . 1524 . Explanation: tan = y x = tan 1 parenleftbigg y x parenrightbigg = tan 1 parenleftbigg 4 . 5 m 4 . 8 m parenrightbigg = 43 . 1524 , so the direction is 43 . 1524 of S of E. 003 10.0 points Consider the instantaneous velocity of a body. This velocity is always in the direction of 1. the net force at that instant. 2. the least resistance at that instant. 3. the motion at that instant. correct Explanation: Solution: The instantaneous velocity vector will always point in the direction of the motion at that instant. 004 (part 1 of 2) 10.0 points A particle has vectorr (0) = (4 m) and vectorv (0) = (2 m / s) . If its acceleration is constant and given by vectora = (2 m / s 2 ) ( + ), at what time t does the particle first cross the x axis? Correct answer: 2 s. Explanation: vectorr ( t ) = vectorr (0) + vectorv (0) t + 1 2 vectora t 2 , so vectorr ( t ) = (4 m) + (2 m / s) t +( 1 m / s 2 ) ( + ) t 2 = [(2 m / s) t (1 m / s 2 ) t 2 ] +[4 m (1 m / s 2 ) t 2 ] vectorr ( t ) will not have a y component when 4 m (1 m / s 2 ) t 2 = 0 (1 m / s 2 ) t 2 = 4 m t = 2 s . schroeder (cs39963) Resource 4: Two Dimensional Motion  Projectile and Circular Moton balasubra 005 (part 2 of 2) 10.0 points At what time t is the particle moving parallel to the y axis; that is, in the direction? Correct answer: 1 s. Explanation: vectorr ( t ) = vectorr (0) + vectorv (0) t + 1 2 vectora t 2 vectorv ( t ) = dvectorr d t = vectorv (0) + vectora t , so vectorv ( t ) = (2 m / s) (2 m / s 2 ) ( + ) t = [(2 m / s) (2 m / s 2 ) t ] (2 m / s 2 ) t vectorv ( t ) will not have an x component when 2 m / s (2 m / s 2 ) t = 0 t = 1 s ....
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 Fall '08
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 Physics

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