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Question
A body of volume 100 cm3 weighs 1 kgf in air. Calculate its weight in water. What is its relative density?
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Solution
Volume of body= 100 cm3 .
Weight of body= 1 kgf = 1000 gf
Mass of body= 1000 gm.
Density of liquid= 1000 gm/100cm3 = 10 gcm3 .
Density of water at 4° = 1 gcm-3 .
Relative density= density of substance/density of water at 4° C
Relative density = 10 gcm3 / 1 gcm3 = 10
Mass of body= 1000 gm.
Densityofwater = 1 g cm-3
Acceleration due to gravity = 10 ms-2
Upthrust = V x p xg.
Upthrust = 100 x 1 xf = 100 gf.
Resultant weight of the body = weight-upthrust = 1000 gf-100 gf = 900 gf.
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