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phy121
Your 'cq_1_27.1' 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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A ball of mass 400 grams is immersed in water. The ball is suspended in the water by a rubber band chain which exerts a tension force of 2.5 Newtons on the ball.
• What is the weight of the ball?
answer/question/discussion: ->->->->->->->->->->->-> :
weight= m*g
= 0.4kg*9.8m/s^2
= 3.92N
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• What is the buoyant force on the ball?
answer/question/discussion: ->->->->->->->->->->->-> :
net force is equal to 0 on the ball, therefore:
3.92N downward, 2.5N upwards
2.5N-3.92N+0= -1.42N
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The buoyant force plus the tension force plus the weight adds up to zero.
Conclusion:
Buoyant force is 1.42 N upward.
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• What therefore must be its volume?
answer/question/discussion: ->->->->->->->->->->->-> :
V= -1.42N/9800N/m^3
V= -0.000145m^3 or -145cm^3
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• What is its density?
answer/question/discussion: ->->->->->->->->->->->-> :
D= m/v
D= 400g/-145cm^3
D= -2.75g/cm^3
Not sure why I had negative numbers, I think I may have switched the values in the buoyant force when subtracting. Or this just means that the ball is going downward? But I feel like I got the right answers but I think the sign is just screwing me up.
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Very good, and you're right that the negative doesn't make sense. Check my note, and also the discussion at the link below. Basically the sum of the three forces is zero, and you didn't quite formulate it that way.
No need for a revision.
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&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new 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.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#