Basic Q's Net Force and Acceleration

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The discussion centers on the accuracy of answers provided in a teacher's guide regarding net forces and accelerations in a physics homework assignment. For question #2, the participant calculates net forces and finds that D has the greatest force, while A, B, and C are equal. The calculated accelerations also show that A and C have the highest values, followed by B and D, which raises questions about the teacher's guide's clarity. In question #3, the participant computes various accelerations and ranks them, agreeing with their own findings. Overall, the conversation highlights discrepancies between student calculations and the teacher's guide answers.
kstbts
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Homework Statement


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Homework Equations


I am wondering if the answers given in the teacher's guide are incorrect.
Ans given for #2: [All same], [A,C,B,D]
Ans given for #3: [A,C,D,B]

The Attempt at a Solution


My answers:
#2a: Net forces: A,B,C are 5N; D is 10N. Therefore the order of the net forces from greatest to least is D, followed by A,B,C which are equal.
#2b: Their accelerations are a) 5N/5kg=1m/s2 b) 5N/10kg=0.5m/s2 c) 5N/5kg=1m/s2 d) 10N/20kg=0.5m/s2. Therefore the order of their accelerations from greatest to least would be A&C, which are the same, followed by B&D which are the same. Admittedly, the teacher's guide could be saying the same thing for this second part of the answer, but I can't be certain since their answer says nothing about A=C and B=D.
#3: Accelerations are:
a) a=(1000N-800N)/(1000N/9.8)=1.96m/s2
b) a=1.23 m/s2
c) a=1.4 m/s2
d) a= 0.98 m/s2
Therefore the order from greatest to least is A,C,B,D
 
Last edited:
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Hi kstbts. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

I like your answers, they are the same as mine.
 
Last edited by a moderator:
Thanks NascentOxygen.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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