Physics_50_Prof_Test_1s_Key

Physics_50_Prof_Test_1s_Key - F 2x = 18 cos (26.4º) = 16.1...

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Physics 50 Proficiency Test 1(sample) (Time: 15 minutes) 25 points By Todd Sauke Name ___________ KEY ________ Section # __ KEY ___ The three forces described below act on an object at the origin of a coordinate system. The given angles are measured counterclockwise around from the + x axis unless other- wise specified. The "newton", letter symbol N, is a unit of force in the metric system. F 1 = 64.0 N at –17 º F 2 = 18.0 N at 0.46 rad F 3 = 47.0 N at 43 º clockwise from the negative y axis. 0.46 rad x (180º / π rad ) = 26.4 º (26) Convert the angle given in rad (radians) to degrees. F 2 = ____ 26.4 ______ º Sketch the three forces as approximately scaled arrows on a coordinate system below. Use enough accuracy to show approximate length and which quadrant each vector is in. Make a vector addition table as in class for summing the components of these vectors and find R x and R y , the components of the "resultant force" (also known as the "net force" or the "vector sum"). F 1x = 64 cos (-17º) = 61.2 F 1y = 64 sin (-17º) = -18.7
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Unformatted text preview: F 2x = 18 cos (26.4º) = 16.1 F 2y = 18 sin (26.4º) = 8.0 F 3x = -47 sin (43º) = -32.1 F 1x = 61.2 F 1y =-18.7 F 2x = 16.1 F 2y = 8.0 F 3y = -47 cos (43º) = -34.4 F 3x =-32.1 F 3y =-34.4 ______________________ _______________________ R x = 45.2 R y =-45.1 (over) ( 45 ) ( -45 ) ( 45 ) ( -45 ) Copy the previous result to this page for convenience: R x = 45.2 R y =-45.1 Sketch another coordinate axis system below, lay off appropriate scales on its axes, and construct the resultant vector R . On your sketch label at least the components of R , the angle from the + x axis, θ R , and an additional convenient angle to help get θ R . Calculate the magnitude of R & the standard angle θ R in degrees & radians. _ ____________ |R| = √ 45.2 2 + 45.1 2 = 63.9 θ R = tan-1 (R y / R x ) = tan-1 ( -0.998 ) = -44.9º -44.9º = -44.9º x ( π rad / 180º ) = -0.784 rad | R | = ___ 63.9 (64) _________ N θ R = ___ -44.9 (-45) _______ º θ R = ____-0.784 (-0.78) ____ rad...
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This note was uploaded on 09/08/2010 for the course PHYS 50 at San Jose State.

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Physics_50_Prof_Test_1s_Key - F 2x = 18 cos (26.4º) = 16.1...

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