cq_1_121

phy201

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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Seed question 12

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= m * a

F= 5kg * 9.8m/s^2

f= 49 newtons

F= 6kg * 9.8 m/s^2

F= 58.8newtons

Fnet= 58.8 - 49 newtons

Fnet= 9.8 newtons

9.8 newtons = 11kg * a

a= .89 m/s^2

#$&*

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: ->->->->->->->->->->->-> :

VO=1.8m/s

a=9.8m/s^2

'dt= 1s

m= 5kg

Not bad, but you haven't declared a positive direction, and your signs are not consistent with the statement of the problem.

Vf= V0 + a * 'dt

Vf= 1.8m/s + 9.8m/s^2 * 1s

Vf= 11.6m/s

F=m * a

F= 5kg * 9.8m/s^2

F= 49newtons

a= f/m

a=49/5kg

a= 9.8m/s^2

#$&*

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: ->->->->->->->->->->->-> :

I think that the velocity and the speed are in the same directions, the systme is speeding up as it accelerates with gravity.

speed doesn't have a direction; speed is the magnitude of velocity

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about 30 minutes

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You weren't careful enough with positive and negative directions. I think you'll understand the solution as given, but if you don't be sure to ask. Otherwise no revision is requested.

&#Please compare your solutions with the expanded discussion at the link

Solution

Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified. &#