Which of the following has the highest specific gravity

Specific Gravity of Different Materials

To determine which of the materials listed has the highest specific gravity, we will compare their specific gravities numerically.

What is Specific Gravity?

Specific gravity is the ratio of the density of a substance to the density of a reference substance, typically water at 4°C. The formula for specific gravity is given by:

For our comparison, we consider the specific gravities of:

• Wood
• Water
• Gold
• Quartz

Numerical Values of Specific Gravities

The specific gravities of these materials are typically:

• Wood: Ranges from 0.4 to 0.9, depending on the type.
• Water: Exactly 1 (since it's the reference substance).
• Gold: Approximately 19.3.
• Quartz: Approximately 2.65.

Conclusion

Given these values, it's clear that the material with the highest specific gravity is gold, with a specific gravity of approximately 19.3.

This exceptionally high value demonstrates gold's significant density relative to water and the other materials listed.

Explanation of Specific Gravity Comparison

Specific gravity is a dimensionless quantity that describes the ratio of the density of a substance to the density of a reference substance (usually water for liquids). Specific gravity comparison involves examining this ratio for different materials to understand their relative densities.

Definition

The formula for specific gravity ($SG$) is:

Importance in Various Fields

1. Material Science:
Knowing the specific gravity of a material helps in identifying it and understanding its properties. For instance, metals with higher specific gravity tend to be denser and may be stronger or more durable.

2. Engineering:
In civil engineering, specific gravity is used to select appropriate materials for construction. For example, aggregates with higher specific gravity are favored for making concrete.

3. Healthcare and Biology:
In medical diagnostics, the specific gravity of bodily fluids like urine is measured to assess kidney function.

Application Example

Consider two liquids, A and B, with densities $\rho_A$ and $\rho_B$, respectively. If we compare their specific gravities with water ($\rho_{H_2O}$):

If $SG_A > SG_B$, it implies that liquid A is denser than liquid B when both are compared to water.

Understanding specific gravity comparison helps in a variety of practical applications, from industrial material selection to routine health check-ups, making it a crucial concept across disciplines.

The Concept of Density of Materials

The density of a material is a measure of how much mass is contained in a given unit volume of that material. It is often denoted by the symbol $\rho$ (rho). Density is a fundamental property of matter, which can help identify a substance and determine its behavior in different conditions.

The formula to calculate density is:

Where:

• $m$ stands for mass
• $V$ stands for volume

Units of Density

The standard unit of density in the International System of Units (SI) is kilograms per cubic meter (kg/m³). However, other units such as grams per cubic centimeter (g/cm³) are also commonly used, especially in chemistry and smaller-scale applications.

Importance of Density

Density plays a crucial role in various scientific and engineering applications:

• Identifying Substances: Different materials have characteristic densities, which can be used to identify unknown substances.
• Material Selection: Engineers and designers choose materials based on their densities to ensure structural integrity and functionality.
• Buoyancy: Objects with densities less than that of a fluid will float, while those with higher densities will sink. This principle is vital in shipbuilding, aeronautics, and fluid mechanics.

Factors Affecting Density

1. Temperature: As temperature increases, most materials expand, increasing their volume and thus decreasing their density.
2. Pressure: Increasing pressure typically decreases the volume of a material, thereby increasing its density.
3. Impurities and Composition: Adding impurities or changing the composition of a material can alter its density.

Examples of Densities

Here are some example densities for various materials:

• Water: approximately $1 \, \text{g/cm}^3$ (or $1000 \, \text{kg/m}^3$)
• Air: approximately $0.001225 \, \text{g/cm}^3$ (or $1.225 \, \text{kg/m}^3$)
• Steel: typically around $7.85 \, \text{g/cm}^3$ (or $7850 \, \text{kg/m}^3$)
• Gold: approximately $19.32 \, \text{g/cm}^3$ (or $19320 \, \text{kg/m}^3$)

Understanding the density of materials helps in grasping how substances interact with each other and with their environment, making it a cornerstone of material science.