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September 9th, 2011, 02:43 AM  #1 
Banned Camp Joined: Aug 2011 Posts: 534 Thanks: 2  Direct and Inverse Variation
DIRECT VARIATION : one quantity increases the other quantity increases or if one quantity decreases the other quantity decreases. INVERSE VARIATION : one quantity increases the other quantity decreases or if one quantity decreases the other quantity increases. Applications in Physics  1. V ? I > Ohm's Law > Voltage is Directly Proportional to Current. As Voltage increases, Current Increases. 2. Speed = Distance / Time > Speed is inversely Proportional to Time. As Speed increases, Time Decreases. Applications in Economics  1. Law of Supply : As the price of a good or service increases, the quantity of goods or services offered by suppliers increases and vice versa. Price ? Quantity of Goods Offered by Suppliers. Price is Directly proportional to Suppliers Supplying Goods. 2. Law of Demand : as the price of a good or service increases, consumer demand for the good or service will decrease and vice versa. Price is inversely proportional to Consumer Demand for Goods. Questions  1. In Maths we have the word "Variation". Variation are into two types > Direct and Inverse. Is Variation and Proportion are Synonyms ? i.e Different words having same meaning. Or there is a difference interpreted in Maths for Variation and Proportion ? can we say Direct Variation is Direct Proportion ? can we say Inverse Variation is Inverse Proportion ?. i.e are they same ? 2. Other than Applications in Physics and Economics, where we can find applications of Direct and Inverse Variation i.e Chemistry, Physiology etc ?. Thanks & Regards, Prashant S Akerkar 
November 6th, 2011, 09:55 PM  #2 
Banned Camp Joined: Aug 2011 Posts: 534 Thanks: 2  Re: Direct and Inverse Variation 
November 10th, 2011, 11:57 AM  #3 
Newbie Joined: Nov 2011 Posts: 7 Thanks: 0  Re: Direct and Inverse Variation
Mathematically, a proportion is an equation with two ratios on each side. It states that two ratios are equal to each other. A direct variation is a specific type of proportion, where there are two variables, x and y, and one constant k, such that they are related like so: y = kx, or written in the "familiar proportion form" y/x = k/1. Inverse variations are another specific type of proportion, with variables x and y, and constant k, such that this relationship ensues: xy = k, or in the "familiar proportion form" y/1 = k/x. So to say a direct variation is a direct proportion is kind of like saying that a red apple is a red fruit. I guess it is always better to be specific, but you would not be entirely incorrect in saying that. Direct and inverse variations only apply to linear equations without a yintercept. Proportions can involve all different types of equations. For chemistry, density and volume vary inversely by the proportion given below (when mass is constant). d = m/v or d/1 = m/v. (as density increases, volume decreases) or (as volume increases, density decreases) when mass is held constant. If I have 20 lb of cheerios, they will take up more space than 20 lb of steel. Steel being more dense than cheerios. Also, m = dv, so mass and volume vary directly(as mass increases, volume increases) when density is held constant. 
November 14th, 2011, 11:11 PM  #4 
Banned Camp Joined: Aug 2011 Posts: 534 Thanks: 2  Re: Direct and Inverse Variation
Thank you. Attaching Image ... Thanks & Regards, Prashant S Akerkar 

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