Society & Culture23 mins ago
Placing a floating object in a water bucket
Does insertion of a floating object in a bucket of water increase the whole unit's weight? Please explain.
Eg.
If the bucket of water weighs 10 kgs, then does the insertion of the floating object of weight 2 kgs increase the whole unit's weight to 12 kgms?
Eg.
If the bucket of water weighs 10 kgs, then does the insertion of the floating object of weight 2 kgs increase the whole unit's weight to 12 kgms?
Answers
Best Answer
No best answer has yet been selected by Siby. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.Loosehead is, of course, perfectly correct (provided placing the object in the water does not cause it to overflow).
However, when I see questions such as this I�m always interested in people�s thought processes and what they were taught and how they learn. Just what other answer did you expect, Siby?
Just think it through. If, for example, you placed both the bucket of water and the object (not yet in the bucket) on scales and saw that they, together, weighed 12kg, why did you expect they should weigh something different when you floated the object in the bucket? Or, if you placed the bucket with the object already floating in it on the scales, noted the weight, and then removed the object and placed it by the side of the bucket (still on the scales) what did you think would happen? Why should you expect the total weight to change, and if it does, where does the change in weight go to or come from?
I�m not having a dig, Siby. You obviously needed to ask the question. I�m just utterly intrigued!
However, when I see questions such as this I�m always interested in people�s thought processes and what they were taught and how they learn. Just what other answer did you expect, Siby?
Just think it through. If, for example, you placed both the bucket of water and the object (not yet in the bucket) on scales and saw that they, together, weighed 12kg, why did you expect they should weigh something different when you floated the object in the bucket? Or, if you placed the bucket with the object already floating in it on the scales, noted the weight, and then removed the object and placed it by the side of the bucket (still on the scales) what did you think would happen? Why should you expect the total weight to change, and if it does, where does the change in weight go to or come from?
I�m not having a dig, Siby. You obviously needed to ask the question. I�m just utterly intrigued!
Actually a volume of air equivalent to the volume of the object inserted is displaced. However, if the object was originally weighed in air of the same density (and same gravity) this would not alter the outcome. Conversely, if this "experiment" was carried out in a vacuum (as ideally it would) then the displacement of air would not be a consideration.
For a while a could never work out the following: Say a man who weighs 15 stone picks up a boy who weighs 5 stone. His arms are then carrying that 5 stone weight . If someone else came along and lifted up the man then he would be carrying 15 st plus 5 st = 20 st. You then have one man carrying 5 st and another carrying 20 st, which adds up to 25 stone. Where has the extra 5 st come from?
matt_london,
You counted the weight of the child twice.
I like this one too http://mathforum.org/dr.math/faq/faq.missing.d ollar.html
You counted the weight of the child twice.
I like this one too http://mathforum.org/dr.math/faq/faq.missing.d ollar.html
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