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Phy 231
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.
** CQ_1_12.1_labelMessages **
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: ->->->->->->->->->->->-> scussion:
F1=6kg*9.8m/s^2=58.8N
F2=5kg*-9.8m/s^2=-49N
Fnet=F1+F2
Fnet=58.8N-49N
Fnet=9.8N in the direction of the heavier mass.
9.8N=Total mass * a
9.8N=11kg*a
9.8kg*m/s^2=11kg*a
.89m/s^2=a
The system is accelerating at .89m/s^2 in the direction of the heavier mass.
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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: ->->->->->->->->->->->-> scussion:
Acceleration still equals .89m/s^2 in the positive direction.
v0=1.8m/s in the negative direction
`dt=1s
.89m/s^2=(vf- -1.8m/s)/1s
.89m/s^2*1s-1.8m/s=vf
-.91m/s=vf
1 second later, the 5kg mass will still be decending (moving in the negative direction), but at the slower speed of .91m/s.
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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: ->->->->->->->->->->->-> scussion:
In the case with the initial push, the first second involves acceleration in the positive direction and velocity in the negative direction, so acceleration and velocity are moving in different directions.
The system is increasing in velocity, but because velocity is negative during that second, it is actually slowing down (getting closer to zero).
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&#Very good responses. Let me know if you have questions. &#