#$&*
phy 201
Your 'cq_1_12.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_12.1_labelMessages **
Masses of 5 kg and 6 kg are suspended from opposite sides of a light frictionless pulley and are released.
What will be the net force on the 2-mass system and what will be the magnitude and direction of its acceleration?
answer/question/discussion: ->->->->->->->->->->->-> :
9.8 m/s^2 on the side with 6 kg
#$&*
@&
If you attach two equal masses by a string, suspend them by the string over a pulley, hold them stationary then release them, they will stay put.
If you add a small mass to one side or another, the masses don't suddenly accelerate at 9.8 m/s^2.
If you add a very large mass to one side, they they will experience an acceleration close to 9.8 m/s^2.
The difference in the masses is a small proportion of the total mass, so the present system isn't going to accelerate at anything close to 9.8 m/s^2.
Can you answer the following:
What is the force on the 6 kg mass?
What is the force on the 5 kg mass?
Do these forces tend to reinforce one another or oppose one another?
What therefore is the net force?
How much mass is being accelerated by the net force?
What therefore is the acceleration of the system?
*@
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: ->->->->->->->->->->->-> :
8 m/s^2 ascending
#$&*
@&
It appears that you might have subtracted 1.8 m/s from 9.8 m/s^2.
9.8 - 1.8 = 8, certainly.
However
9.8 m/s^2 - 1.8 m/s =
9.8 m/s * ( 1/s - .176).
You can't subtract .176 from 1/s. The two are not like terms.
Nor are 9.8 m/s^2 and 1.8 m/s like terms.
You can't add or subtract a velocity and an acceleration. Velocity and acceleration measure completely different things, and are not like terms. They are not compatible for addition or subtraction.
*@
During the first second, are the velocity and acceleration of the system in the same direction or in opposite directions, and does the system slow down or speed up?
answer/question/discussion: ->->->->->->->->->->->-> :
in the first situation yes and it speeds up , in the second situation no and its slowing down
#$&*
*#&!*#&!
@&
You'll need to rework this entire problem.
See my notes and answer my questions, which should give you a better feel for this system. Then rework the remaining questions.
Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes.
*@
#$&*
phy 201
Your 'cq_1_12.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_12.1_labelMessages **
Masses of 5 kg and 6 kg are suspended from opposite sides of a light frictionless pulley and are released.
What will be the net force on the 2-mass system and what will be the magnitude and direction of its acceleration?
answer/question/discussion: ->->->->->->->->->->->-> :
9.8 m/s^2 on the side with 6 kg
#$&*
@&
If you attach two equal masses by a string, suspend them by the string over a pulley, hold them stationary then release them, they will stay put.
If you add a small mass to one side or another, the masses don't suddenly accelerate at 9.8 m/s^2.
If you add a very large mass to one side, they they will experience an acceleration close to 9.8 m/s^2.
The difference in the masses is a small proportion of the total mass, so the present system isn't going to accelerate at anything close to 9.8 m/s^2.
Can you answer the following:
What is the force on the 6 kg mass?
What is the force on the 5 kg mass?
Do these forces tend to reinforce one another or oppose one another?
What therefore is the net force?
How much mass is being accelerated by the net force?
What therefore is the acceleration of the system?
*@
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: ->->->->->->->->->->->-> :
8 m/s^2 ascending
#$&*
@&
It appears that you might have subtracted 1.8 m/s from 9.8 m/s^2.
9.8 - 1.8 = 8, certainly.
However
9.8 m/s^2 - 1.8 m/s =
9.8 m/s * ( 1/s - .176).
You can't subtract .176 from 1/s. The two are not like terms.
Nor are 9.8 m/s^2 and 1.8 m/s like terms.
You can't add or subtract a velocity and an acceleration. Velocity and acceleration measure completely different things, and are not like terms. They are not compatible for addition or subtraction.
*@
During the first second, are the velocity and acceleration of the system in the same direction or in opposite directions, and does the system slow down or speed up?
answer/question/discussion: ->->->->->->->->->->->-> :
in the first situation yes and it speeds up , in the second situation no and its slowing down
#$&*
*#&!*#&!
@&
You'll need to rework this entire problem.
See my notes and answer my questions, which should give you a better feel for this system. Then rework the remaining questions.
Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes.
*@