cq_1_193

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Phy 121

Your 'cq_1_19.3' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.

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Asst 19 Question 3

An object moving in the direction 120 degrees (as measured counterclockwise to the positive x axis) encounters a net force whose direction is 270 degrees. 

• Sketch the force and its component along the line of motion, as well as its component perpendicular to the line of motion.

answer/question/discussion: ->->->->->->->->->->->-> :

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• Suppose you are facing in the direction of motion.  Do you perceive the component of the force along the line of motion to be forward or backward?  It this component in the direction of motion or opposite to the direction of motion?

answer/question/discussion: ->->->->->->->->->->->-> :

120 degrees is direction of motion, you have to turn 150 degrees to be at the direction of the force(270 deg). If you were in opposite direction of motion, then you would have to go 30 degrees to face the direction of the force.

I would say the vector is close to the opposite direction of motion.

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Good.

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• Will the object speed up, slow down or maintain a constant speed? 

answer/question/discussion: ->->->->->->->->->->->-> :

 The object should slow down, since it is closer to the backwards motton.

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• If you are facing in the direction of motion, then the line perpendicular to the direction of motion will run to your right and to your left.  Is the component of the force perpendicular to the line of motion directed to the right or to the left? 

answer/question/discussion: ->->->->->->->->->->->-> :

 Facing 120 deg, to get to 270 deg you have to turn 150 degrees ot the left or 210 degrees to right. ??? I am not sure what else to say???

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You would want to sketch the two vectors, and the components of the net force in the direction of motion, and perpendicular to the direction of motion.

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• Will the object veer to the right, to the left or maintain straight-line motion? 

answer/question/discussion: ->->->->->->->->->->->-> :

 The object will veer to the left since it is 150 deg from 270 deg.

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• Which is greater in magnitude, the component of the force along the line of motion or the component perpendicular to the line of motion?

answer/question/discussion: ->->->->->->->->->->->-> :

 270-210=150 deg. 150 deg-120 deg (motion direction)= 30 deg parallel to motion. Force is 60 degrees from perpendicular direction. Parallel is greater than the perpendicular direction.

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15 min

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You've done some good thinking here.

Compare your thinking with that of the discussion at the link. No revision necessary unless you have questions.

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&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.

Then please compare your old and new solutions with the expanded discussion at the link

Solution

Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.

If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#