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:
F1 = 5 * 9.8 = 49 N
F2 = 6 * 9.8 = 58.8 N
Fnet = F2 – F1 = 9.8 N going straight down in the direction of gravity.
• 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:
since the acceleration is in favor of the 6kg weight, it will be negative on the 5kg side.
a = (vf-v0)/’dt
-9.8 = vf – 1.8
Had you used units you would have written
-9.8 m/s^2 = vf – 1.8 m/s or
-9.8 N = vf - 1.8 m/s
The right-hand side has units m/s and the left-hand side has units m/s^2 or N, whichever you intended; in either case the two sides can't possibly be equal. They are incompatible for addition or subtraction.
To get started on this question you have to first figure out the acceleration of the system, which is F_net / m.
vf = -8 m/s
the speed 1 second later will be 8 m/s and it will be ascending.
• 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:
during the first second, the velocity starts in the opposite direction of acceleration. The velocity will slow and stop for a moment then start in the other direction, the same as that of acceleration, speeding up as time increases.
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15 min
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&#At least part of your solution does not agree with the solution and comments given at the link below. You should view the solution at that link and self-critique as indicated there.
Solution
This link also expands on these topics and alerts you to many of the common errors made by students in the first part of this course. &#