Question

What is the unit of relative density. Why an iron needle sinks in water, but a

ship made of iron floats on water. Explain
​

Answer 1

QUESTION

What is the unit of relative density.

ANSWER

Relative density is a ratio of the density of a certain material to the density of a reference material. Relative density has no unit, because the units of the material in question cancel out with the units of the reference material.

QUESTION

Why an iron needle sinks in water, but a

ship made of iron floats on water. Explain

ANSWER

An iron needle sinks in water, but a ship made of iron floats on water Because the specific gravity of the needle is greater than that of water displaced by it.

Specific gravity (or relative density) is given by:

$\tt\red{ \frac{Density \: of \: Substance \:}{Density \: of \: Water \: \: at \: 4 oC} </p><p> }$

The average density of iron needle is greater the water, therefore, it sinks.

Answer 2

Answer:

Relative density is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material (i.e., water). It is usually measured at room temperature (20 Celcius degrees) and standard atmosphere (101.325kPa). It is unitless.

The iron ship is constructed in such a way that it is mostly hollow from within Hence the average density of the ship is less than that of water (i.e. less than 1 g/cm ^ 3) wheres iron needle being compact and its density is 7.6g/cm ^ 3 which is more than 1 g/cm ^ 3 (density of water) Hence the needle sinks in water.

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