Question Details

The relative density of material of a body is found by weighing it first in air and then in water. If the weight in air is (5.00 ± 0.05 ) Newton and weight in water is (4.00±0.05) Newton. Then the relative density along with the maximum permissible percentage error is

Options

A

5.0 ± 11%

B

5.0 ± 1%

C

5.0 ± 6%

D

1.25 ± 5%

Correct Answer :

5.0 ± 11%

Solution :

The correct option is 5.0 ± 11%.

Step-by-step Explanation:

Relative density (R.D.) of a material is defined as the ratio of its weight in air to the loss of its weight in water.
Let:
Weight in air, W1=(5.00±0.05) N
Weight in water, W2=(4.00±0.05) N

The loss of weight in water (W) is given by:
W=W1-W2

Substituting the values:
W=5.00-4.00=1.00 N

The absolute error in the loss of weight (ΔW) is the sum of the absolute errors in the individual measurements (since errors add up during subtraction):
ΔW=ΔW1+ΔW2
ΔW=0.05+0.05=0.10 N

So, the loss of weight in water is:
W=(1.00±0.10) N

Now, the relative density (R.D.) is calculated as:
R.D.=W1W
R.D.=5.001.00=5.0

The relative error in relative density (ΔR.D.R.D.) is given by:
ΔR.D.R.D.=ΔW1W1+ΔWW

Substituting the values into the error formula:
ΔR.D.R.D.=0.055.00+0.101.00
ΔR.D.R.D.=0.01+0.10=0.11

To find the maximum permissible percentage error, multiply the relative error by 100:
Percentage Error=0.11×100%=11%

Therefore, the relative density along with the maximum permissible percentage error is:
5.0 ± 11%

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