cq_1_121

phy 201

Your 'cq_1_12.1' 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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Masses of 5 kg and 6 kg are suspended from opposite sides of a light frictionless pulley and are released. •What will be the net force on the 2-mass system and what will be the magnitude and direction of its acceleration?

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

The Net force would be 5kg x 9.8m/s^2 = 49N 6kg x 9.8m/s^2 = 58.8N

49N + 58.8N = 107.8N

58.8N-49N = 9.8 N in the downward direction

• If you give the system a push so that at the instant of release the 5 kg object is descending at 1.8 meters / second, what will be the speed and direction of motion of the 5 kg mass 1 second later?

answer/question/discussion: ->->->->->->->->->->->-> : 9.8 - 1.8 = 8 m/s downward

9.8 and 1.8 are not represented with units. I suspect the 1.8 represents the 1.8 m/s decrease in vertical velocity, but it's not clear what vertical velocity the 9.8 might represent. I suspect confusion with the acceleration of gravity, which has already been taken into account in calculating the acceleration of the system.

• During the first second, are the velocity and acceleration of the system in the same direction or in opposite directions, and does the system slow down or speed up?

answer/question/discussion: ->->->->->->->->->->->-> : They are in opposite directions, the system slows down, because the 5 kg object is moving up naturally, and then you pull it down 1.8m/s so it would then move at 8m/s.

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20 minutes

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Solution

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