Question

The relative density of material of a body is found by weighting it first in air and then in water . If the weight in air is `( 5.00 +- 0.05) N` and the weight in water is `(4.00 +- 0.05) N`. Find the relative density along with the maximum permissible percentage error.

Answer 1

Weight in air ` = ( 5.00 +- 0.05) N`
weight in water `= ( 4.00 +- 0.05 ) N`
Loss of weight in water `= ( 1.00 +- 0.1 ) N`
Now relative density `= ( "weight in air")/( "weight loss in water")`
i.e., `RD = ( 5.00 +- 0.05) /( 1.00 +- 0.1)`
Now relative density with maximum permissible error
`= (5.00) /( 1.00) +- (( 0.05)/( 5.00) + (0.1)/(1.00)) xx 100`
`= 5.0 +- (1+10)% = 5.0 +- 11%`