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Question
A test tube loaded with lead shots weighs 25 gf and floats upto the mark X in water. When the test tube is made to float in brine solution, it needs 5 gf more of lead shots to float upto level X. Find the relative density of brine solution.
Solution
When test tube floats is water:
Weight of test tube = 25 gf
By law of floatation
Weight of water displaced = Weight of test tube = 25 gf
When test tube floats in a brine solution, it needs 5 gf more of lead shots to float up to same level as in water.
Weight of test tube = 25 + 5 = 30 gf
By law of floatation :
Weight of brine solution displaced = Weight of test tube = 30 gf As, volume of brine solution displaced = Volume of water displaced
∴ R.D. of brine solution = `"Weight of brine solution displaced"/"Weight of water displaced"`
`= 30/25 = 1.2`
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