Dimensional AnalysisSolving Conversion Problems

Objective • SWBAT use dimensional analysis to solve unit

conversion problems.

How To: Use Dimensional Analysis

1. Take lone number (given in problem) and place over 1.

2. Multiply by conversion factors. Make sure units cancel diagonally. (New units on top!)

3. Multiply across and simplify. 4. Check units of final answer.

Dimensional Analysis

• Dimensional analysis is just a method for solving conversion problems.

• It’s based on the math principle that units cancel when divided:

• We also use conversion factors as ratios between quantities.

How To: Use Dimensional Analysis1. Take lone number (given in problem) and place

over 1.2. Multiply by conversion factors. Make sure units

cancel diagonally. (New units on top!)3. Multiply across and simplify. 4. Check units of final answer.

Example

• George has 2 hands. How many fingers does he have?

Example

• A book is 0.45 feet long. How many inches is it?

Practice

• Ms. Holli-Arcus slept for 5.4 hours. How many minutes did she sleep?

More Complex Problems

• Sometimes, you will need to use multiple conversion factors to solve a problem.• Go slow and check that all of your units cancel

except for your final units. Remember: new units go on top!

Example

• The oldest person to ever live died at the age of 122 years old. How many hours old was she?

Example

• Most classes here at Northtown are 1 hour long. How many seconds long is each class?

Practice

• Ms. MacQueen flew 1,100 miles home to Texas for winter break. How many inches did she fly?