# Relative Density of Substances and Specific Gravity

#### Academic Questions in PhysicsPlease check out our Test Your Knowledge page to see all Questions and Answers The rate of change of momentum is proportional to the applied force and will take place in the direction of that force. The above statement is attributed to _____. A. Albert Einstein B. Isaac Newton C. Galileo Galilei D. Neils Bohr E. Ernest Rutherford F. Marie Curie The Law of Inertia is also referred to as _____. A. 1st Law of Thermodynamics B. 2nd Law of Thermodynamics C. 3rd Law of Thermodynamics D. Newton's 1st Law of Motion E. Newton's 2nd Law of Motion F. Newton's 3rd Law of Motion The process whereby the velocity of an object increases and decreases over a period of time is best associated with the term _____. A. Speed B. Velocity C. Momentum D. Constant Velocity E. Acceleration F. Average Velocity The rate of motion is best referred to as _____. A. Speed B. Velocity C. Momentum D. Inertia E. Acceleration F. Constant Velocity Consider this expression below: A body X exerts a force FX on another body Y. In return, body Y exert a force FY back on body X. The forces FX and FY are equal in magnitude but opposite in direction. Putting the above expression into equation: FX = -FY Where FX is the action force FY is the reaction Force The above expression relates to _____. A. Theory of Force B. Force Postulate C. Einstein's proposal on Relativity D. Newton's 1st law of motion E. Newton's 2nd law of motion F. Newton's 3rd law of motion The tendency of a body to remain in a state of rest or in uniform motion is referred to as _____. A. Tension B. Uniform acceleration C. Constant acceleration D. Deceleration E. Inertia F. Velocity A change in the position of an object with reference to time is best described as _____. A. Momentum B. Displacement C. Velocity D. Acceleration E. Direction F. Motion The saying 'what goes up on earth must come down' can be best attributed to _____. A. Force B. Motion C. Mass D. Acceleration E. Average velocity F. Constant velocity ### Relative Density | Specific Gravity:

Density is an important unit of measurement. This is so because equal volumes of different substance have got their respective masses and weights.

Density is simply defined as the mass of a unit volume of a material or substance.

Note: An understanding on Density will aid you to better comprehend the concept of relative density.

Relative density involves the density of one substance in relation to that of water (at 4oC). it's also called specific gravity.

The Relative Density (R.D) of a material is the ratio of it's density (the material) to that of water at 4oC.

By principle, an object with a specific gravity or relative density of less than 1 will float on water, while that with value greater than 1 will sink in water.

Below is a summary of formulas for calculating Relative Density:

Relative Density - R.D = Mass of Substance/Mass of Water at 4oC

R.D = Weight of Substance/Weight of Water

R.D = Density of Substance/Density of Water at 4oC

R.D = ρsubstance / ρreference (water at 4oC)

Where ρ = Density

Note: Relative Density has no Standard International (SI) unit.

The table below shows the Relative Density of some substances:

 SUBSTANCE RELATIVE DENSITY Balsa Wood 0.2 Oak Wood 0.75 Ethanol (C2H5OH) 0.78 Liquid Paraffin 0.8 Olive Oil 0.91 Coconut Oil 0.925 Petroleum 0.98 Water (Fresh Water) 1 Salt Water (Reef Aquarium) 1.025 Ironwood 1.5 Graphite 1.9 – 2.3 Common  Salt (NaCl) 2.17 Aluminium (Al) 2.7 Cement 3.15 Iron  (Fe) 7.87 Copper (Cu) 8.96 Lead (Pb) 11.35 Gold (Au) 19.3 Osmium (Os) 22.59 Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

Please Register here or Login here to contribute to this topic by commenting in the box below.

CONTRIBUTE TO THIS TOPIC | ASK A QUESTION