Question:medium

An undisturbed soil sample is collected from a field with core cylinder having an internal diameter of \(60\) mm and length of \(100\) mm. The weights of moist soil and oven dried soil are \(0.48\) kg and \(0.44\) kg, respectively. Assuming density of water as \(1000\) kg/m\(^3\), the water depth (in metres per metre depth of soil) is ________ (Rounded off to two decimal places)

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Find the mass of water lost on drying and convert its volume into an equivalent depth.
Updated On: Aug 6, 2026
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Correct Answer: 0.14

Solution and Explanation

Step 1: Get the sample volume and the water mass lost on drying.
$V = \dfrac{\pi}{4}(0.06)^2(0.1) \approx 2.827\times10^{-4}$ m$^3$, and the moist sample lost $0.48-0.44=0.04$ kg of water on drying.

Step 2: Work directly in volumetric water content instead of depths.
Volume of that water: $V_w = 0.04/1000 = 4\times10^{-5}$ m$^3$.
Volumetric water content is just this water volume as a fraction of the total sample volume: \[ \theta = \frac{V_w}{V} = \frac{4\times10^{-5}}{2.827\times10^{-4}} \approx 0.1415 \]
Step 3: Use the fact that volumetric water content equals depth of water per unit depth of soil.
For any soil column of uniform cross-section, $\theta$ already carries the units of (m water)/(m soil), since both the water volume and the soil volume share the same cross-sectional area. So no separate depth calculation is needed.

Final Answer:
The volumetric water content, and hence the water depth per metre of soil, comes out to about $0.14$. \[ \boxed{\approx 0.14} \]
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