A cuboidal block of iron (6.8g/cc) ans mass=1kg is immersed in water upto 1/2 its height.
A spring with force constant K= 1N/m presses the block from above. Non-deformed length of the spring was 50cm.
Find the normal reaction on the block (at its bottom surface).
25.03??
ReplyDelete2.85 N ?
ReplyDelete9.51
ReplyDelete9.514705 N
ReplyDeletethis shows 2 things:
ReplyDelete1)people are still reading the blog and willing to answer simple, yet interesting problems.
2)we have got 4 wrong answers!!!
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ReplyDeleteHi Anonymous:
ReplyDeleteWe post the answers, not the solutions. That's why i had tried to block 'Anonymous' commenting once.
Sorry bhaiya...and i think i made a calculation error the ans was 10.25N
ReplyDeletebtw how would blocking anonymous commenting stop people from posting solutions i mean followers too can post solutions
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ReplyDelete9.33N?
ReplyDeletebhaiya what is the correct answer?
ReplyDelete10.25N if you take |g|=10
ReplyDeleteinteresting problem. rather an interesting situation. will buoyant force act here?
ReplyDeleteby what we have learnt, it should act because the object has displaced water. but there is no surface on which water pressure vud act in upward direction. plz help.
anyways, i agree with 10.25 if |g|=10
yes pressure would act but area on which it act is zero so no boyant force
ReplyDelete@anonymous.. No it wont..(agree with shivam)
ReplyDeleteAmazing question bhaiya! (:
nice question :)
ReplyDeleteyup..this was a question in a 100percentile test.
ReplyDeleteand i did it wrong, i.e. i took the buoyant force.
the question deals with the origin of the buoyant force. i have another similar question, which i might post soon.
what will be the answer if its a 4*1*1 cuboid, and the water is filled to a height of 4.10 m?
ReplyDeleteI think same answer i.e. 10.25
ReplyDelete1010.25
ReplyDeleteWow! completely forgot this very basic concept...
ReplyDeleteI think that buoyant force will act.....We cant create a vacuum situation underneath the block,therefore a very small layer of water will be present
ReplyDeleteand even if we dont consider that how can the answer be 10.25, where will the atmospheric pressure on the top be cancelled
i completely agree with anonymous
ReplyDelete1)"Here's something you can try: put a heavy rubber block in a dry glass beaker and THEN fill it with water, chances are it will stay there. (of course you'll have to hold it down while you are filling the beaker.)"
ReplyDeleteNormally, the rubber block floats in water.
2)We should consider atmospheric pressure. 63N/cm.
http://www.youtube.com/watch?v=7t_-2L7SQkQ
convincing....
ReplyDelete1.if the air gap beneath the block is made to be approximately 0,almost a vaccum situation,the block wont move?
ReplyDelete2..i have a doubt in the video.when the person pulled it up from point on the corner he could pull it up easily.but not from the middle of the sheet.why so? isnt equal pressure acting on every point on the sheet?
1)I won't think in terms of a vacuum. Lets keep things simple. Pascal's law is valid only for continuous liquids.
ReplyDelete2)Watch this too:
http://www.videojug.com/film/how-to-put-a-ruler-under-pressure-2
You could break the ruler by a 'karate chop'.
Suppose in a beaker there is a column of oil above a column of water and a block is at the interface of the 2 liquids such that a portion of it is inside water and the other in oil. When solving such questions why do we take buoyant force exerted by oil even though there is no oil below the surface of the block?
ReplyDeletehi shubham if u are getting confused with archemidies law u can do it by pascal's law dreaw the pressure at the all surfaces and try to figure out the net external pressure because archemideise law is derived from pascal's law..
ReplyDelete