need chemistry help! 10 easy pts?

A

ATL FALCONS FAN

New member
What is a good example of how I might use dimensional analysis to solve a simple problem?

also another question is How does uncertainty enter into measurement? how is uncertainty indicated in scientific measurements?

And finally why must a unit be included with a measurement?
Thanks
 
you can use dimensional analysis to convert from feet to inches



a unit must be included with a measurement to tell the people what you were measuring in (i.e. feet, inches, grams,..)
 
First Question: Dimentional analysis refers to making a measurement, like measuring length with a ruler, or time with a clock, or temperature with a thermometer. So using a thermometer to check for a fever is a way to use dimensional analysis to solve a simple problem.

Second Question: Uncertainty enters into measurement because sometimes it is difficult to tell where the correct measurement is. For example, if you use a ruler to measure the length of a piece of chalk, you may not be quite sure if its about 2.0 inches or more like 2.2 inches.

Uncertainty is indicated with a "plus or minus" sign, which is a plus sign on top of a minus sign (±), followed by the amount of error. So, for example with the chalk, you would say: 2.1 inches ± 0.1 inches (which means 2.1 inches plus or minus 0.1 inches). This is basically a way of saying the correct answer is somewhere in between 2.0 and 2.2 inches.

Third Question: A unit must be included with a measurement in order to give the measurement meaning. If you tell me that a piece of wood is 5 long, that doesn't mean anything, but if you tell me that it is 5 inches long or 5 feet long, that tells me something about the length. In this case inches and feet are units, and they add meaning to the measurement "5."
 
Well here I'll lay them out for you the reason we use dimensional analysis is not quite simply to convert from a specific unit but because we are able to manipulate the data given for example we already know about Area, Lengths, Mass well all those things take up a volume and when you doing your thing in the lab for chemistry it changes the chemical properties which changes the weight we just use them as a means of balancing it in a way like the old law " Matter cannot be created nor destroyed " which means the difference has to go somewhere.


Well uncertainty all it is just taking in account the room for error because not all instruments and measuring devices and are created perfectly its like when you look at a ruler not every single ruler is accurate, which is why you would take its uncertainty of that tool. In engineering we indicated it by a + and - ( Plus or minus) then what ever the number is.

The reason you want to include the unit it simply because its just for habit a number without a unit is meaningless.
 
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