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Unformatted text preview: ME 270  Fall 2009 ' Name
Examination No. 3 ' M Jones Li Murphy Krousgrill Nauman INSTRUCTIONS Begin each problem In the space provided on the examination sheets. if additional space is
required, use the yellow paper provided to you.  Work on one side of each sheet only, with only one problem on' a sheet. . Each problem is worth 20 points. Please remember that for you to obtain maximum credit for a problem, it must be clearly
presented, Le. . the coordinate system must be clearly identified.  where appropriate, free body diagrams must be drawn. These should be drawn
separately from the given figures. . units must be clearly stated as part of the answer.
0 you must carefully delineate vector and scalar quantities. If the solution does not follow a logical thought process, it will be assumed in error. When handing in the test, please make sure that all sheets are in the correct sequential order and make sure that your name is at the top of every page that you wish to have
graded.   . Problem 1
Problem 2 Problem 3 ~—.—.—__ Total ———__*_ ME 270  Fall 2009 Name Examination No. 3 Problem 1a  Kinematics (6 points). A pin travels along a path denoted by the expression r = Zsin(t9), where r is in meters and 9 is in radians. When 0 = 7c/6 radians, 6'? = 0.5 rad/s and § = Orad/sz, please determine the
velocity vector in polar coordinates and the acceleration vector in polar coordinates. ME 270  Fall 2009 ' Name
EXamlnation No. 3 ' (a) (b) ME 270—Fau 2009 » . .Name . '
Examination No.3 .. . , Problem 1d “Kine ‘, _. . . 1 mine the co'né'tarit speed the block must have if
there no normal force at point B. . ME; 270 _ Fan 2009
Examination No'. 3  2 seconds (2 pbints). ME 270 ~ Fan 2009 ' Na‘me
Examination N6. 3 ' Zc. The magnitude of the velocity '17] when t: 2,s.ecoﬁds .(2 points). 2d. The acceleration vector “ ' a m r'ECtangular' coordinates when t= 2 seconds (2 points). a: ll? 7L4"; M/sz" 2e. The magnitude of the acceleration [a] when t: 2 seconds (2 points). .. v: [2.2. Eh. 5" ‘ ME 270 — Fall 2009
Examination No. 3 e . ME 270 : Fall 2009 Nam
Examination No. 3 ' 3. The‘hlock shoWn issittinginside a cbne sectiOn. ;At,th'e moment of interest the block is a
fixed distance (0.2 meters] from the axis of rotation.. The block has 'a mass of Zkg. The
outside angle of the cene is 30° as shOwn.‘ Please show all Work as you complete Ba and 3b. 3a. Consider the situation when there is no reliance onfriction uk,s=0.
‘ Begin with a freebody diagram for the Case with no friction (4 points).
Determine the angular rate of rotation} go, to keep the box at its current location
when there is no frictional'f‘orce v(_6.point's). ' ‘ 1— 0.2m
W, , . ME. 270 — Fall 2009
Examination No. 3 Name..___,____‘__._______._____..___ 3b. Consider the situation when friction is required to keep the block in place and the
friction coefficients (static and kinetic) are 1.11: 540 5.
Begin with a free body diagram for the. case where frictiOn prevents the block
from moving (4 points). ' ~ 
Determine the maximum angular rOtatijon that can be achieved without allowing
the block to slip (6 159mm." U1 ., $3.12. Wot/s ...
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 Spring '08
 MURPHY

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