Wednesday, September 16, 2009

Physical Science Wed Stuff

Density is an intensive (does not depend on amount) property of the object.

Density = mass/volume, typically units are g/ml

The old standby "Cross Multiply and Divide". This can be used when you have two ratios equal to each other.


Step 1- Cross multiply numerator on the left side x denominator on the right. In our example (ad)

Cross multiply denominator on the left side x numerator on the right. In our example (bc)

So we get ad=bc

Let's solve for the four variables.

Step 2 - Divide,

Solving for a ad/d= bc/d ------> a= bc/d

Solve for d ad/a= bc/a -------> d= bc/a

Solve for b ad/c = bc/c -------> ad/c = b

Solve for c ad/b = bc/b --------> ad/b = c

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