Dimensional Analysis

Just like converting between curriences in Chemistry, it is usually necessary to convert between units

The process is called Dimensional Anaylis

Steps:

Find a unit equality

Find the converstion factors

Apply conversion factor

Cancel units

Taught Throughly Click the Link:

Multiple Step Dimensional Anaylsis

Scientific Notation & Significant Digits

Scientific Notation

Scientific Notation is used to show really big or really small numbers easily by an equation.

Example: 2000 = 2.0 x 10^3

4500000 = 4.5 x 10^7

       0.000010 = 1.0 x 10^-5

Significant Digits

Significant Digits are used to be more precise and accurate with calculations.

-Precision and accuracy are very important

-Calculators are not smart enough to give a precise and accurate number 

-Scientist have made rules to round off extra digits: These are a must!

-Non-zero digits are always significant

-If the zero is in the area to the right of the decimal then it is generally not significant

-0.0056

-Any digits to the left of a decimal point are significant

-5.00, 26.68, 18.1400

-Zeros after another number are significant

-2.00, 0.0002100, 5.870

Quick Note:

When Subtracting or Adding, round to the least precise number.

9.65471-6.21 = 3.44471

   = 3.44

   6.4798+3.254 = 9.7338

  = 9.734 

Si System, Percent Error and Experimental Accuracy

On monday, september 21^st we learned about the Si System, Percent error and experimental accuracy.

When you use prefixes with Si Units,you can put a prefix in front of the unit and change the power of it.

The Si system uses many prefixes to represent very large or small numbers.

Note: Don’t mix up scientific notation and prefixes together, theres a big chance you will get confused.

Experiment Accuracy:

the maximum accuracy of any measurement is ½ of the smallest division of the measuring device.For example:A ruler with measurements of millimeters has a mamimum accuracy of + or – 0.5m.

Liquid in a gratuated cylinder will typically form a curved top called a MENISCUS. The volume is taken at the bottom of the meniscus.

Expressing error:

There are 3 types of error

1. Physical error in the measuring device
2. Sloppy measuring
3. Changing ambient conditions

Usually you can’t prevent physical error and changing ambient conditions but you can prevent sloppy measuring.

Absolute error and percentage error:

To get absolute error, it is measured value – accepted value.

To get percent error: