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Phy 241
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: ->->->->->->->->->->->-> :
F_a=m*a
= 6kg*9.81m/s^2
= 58.86 N
F_b=m*a
= 49.05 N
F_net = 9.81N
F_net = m*a
a= F_net/m
= 9.81N/11kg
= 0.89 m/s^2
Direction: -y direction
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One mass rises as the other falls, so they are moving in opposite directions along the y axis. So without more information the y direction cannot define the direction of motion.
If you want to specify that the positive direction is that in which the more massive object is moving in the negative y direction, that is OK.
More often we use the direction of rotation to define the direction of motion, with either clockwise or counterclockwise being chosen as the positive direction.
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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: ->->->->->->->->->->->-> :
v = 1.8 m/s
F = m*a
a = (9.81N) / 11kg
= 0.89 m/s^2
vf = v0 + a * `dt
= -1.8m/s + 0.89*1s
= -0.91 m/s
Speed is 0.91 m/s direction is descending
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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: ->->->->->->->->->->->-> :
Velocity and acceleration are in the same direction.
The system speeds up at a constant acceleration
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You haven't completely specified your positive direction.
If you define the positive direction as the direction in which the more massive object is moving in the negative y direction, then your solutions are correct.
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