Yahoo Answers: Answers and Comments for Fluid Mechanics [其他  科學]
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From 神風
zhHantHK
Thu, 16 Apr 2015 18:01:50 +0000
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Yahoo Answers: Answers and Comments for Fluid Mechanics [其他  科學]
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From 天同: (i) Volume of box = (pi x 0.5^2) x 0.4 m^3 = 0...
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https://hk.answers.yahoo.com/question/index?qid=20150416000051KK00059
Thu, 16 Apr 2015 18:51:36 +0000
(i) Volume of box = (pi x 0.5^2) x 0.4 m^3 = 0.3142 m^3
Weight of box = 0.3142 x 900g N = 2827 N
[Take g, the acceleration due to gravity, to be 10 m/s^2]
(ii) Upthrust = 2827 N
Mass of water displaced = 2827/g kg = 282.7 kg
Volume of water displaced = 282.7/1000 m^3 = 0.2827 m^3
Hence, h = 0.2827/(pi x 0.5^2) m = 0.3599 m
(iii) Pressure = 0.3599 x 1000g N/m^2 = 3599 N/m^2
(iv) Upthrust when box is totally immersed
= 0.3142 x 1000g N = 3142 N
Hence, force required = (3142  2827) N = 315 N