Lecture Notes: Week 2

Two common unit systems:

1. English System used in USA: inches, yards, gallons, Fahrenheit, etc. 2. Metric System used in most of the world: meters, grams, Celsius, etc.

The Standard Units:

1. Length in centimeters (cm), millimeters (mm), meters (m), kilometers (km), etc. 2. Mass in milligrams (mg), grams (g), kilograms (kg), etc. = measure of the quantity of matter in the object. 3. Time in seconds(s), minutes, hours, days, etc. 4. Temperature in centigrade (° C) and Kelvin (K)

General Problem-Solving Strategy:

1. Put the desired final unit or units followed by an equal sign. 2. List the given data with corresponding units. 3. List the needed conversion factors with their corresponding units. 4. Arrange the data and conversion factors so the undesired units will cancel and what is left are the desired units. 5. Perform the mathematical operations to arrive at the final numerical value. 6. Recheck your math and make sure to record your final answer with the desired units obtained from step 4. 7. Make sure to put all final answers in the correct number of significant figures.

2. Select the answer in the correct number of significant figures for how many inches there are in 0.55 meters? A. 2.17 inches B. 23 inches C. 22 inches D. 21.65 inches

2. C

10. If iron (Fe) has a density of 7.86 g/ml, what is the volume of 22.5 g of iron? A. 2.86 ml B. 28.6 ml C. 3.49 ml D. 0.349 ml

A. 2.86 ml

7. Convert 8.1 hours into seconds. A. 2.9 x 10^4 B. 2.9 x 10^3 C. 2.9 x 10^2 D. 2.9 x 10^6

A. 2.9 x 10^4

4. Select the best answer for the conversion of 7.5 liters into quarts. A. 7.9 B. 7.14 C. 714 D. 79.3

A. 7.9

1. Conversion factors are used in the factor-label method to help convert units without changing the inherent value of the given data and without influencing the number of significant figures in the final answer. A. Always B. Rarely C. Sometimes D. Never

A. Always

8. If 23.6 g of a liquid has a volume of 15.6 ml, what is its density? A. 0.661 g/ml B. 1.51 g/ml C. 2.55 g/ml D. 15.1 g/ml

B. 1.51 g/ml

3. Select the answer in the correct number of significant figures for the conversion of 65 kilometers into miles. A. 4.04 miles B. 40. miles C. 41 miles D. 4040 miles

B. 40. miles

6. How many milligrams are there in 9.8 grams? A. 9.8 x 10^3 B. 9.8 x 10^3 C. 980,000 D. 98,000

B. 9.8 x 10^3

5. If you have 5 x 10^4 pounds of iron, how many kilograms do you have? A. 1.1 x 10^5 B. 1.1 x 10^4 C. 4.41 x 10^5 D. 2 x 10^4

D. 2 x 10^4

9. What is the mass of 355 ml of water at 20 degrees C if the density of water at that temperature is 1.00 g/ml? A. 35.5 g B. 1.00 g C. 3.55 g D. 355 g

D. 355 g

Common Units and their equivalents: Length-

Length 1 kilometer (km)= .6214 mile (mi) 1 meter (m)= 39.37 centimeters (cm) or 1.094 yards (yd) 1 foot (ft)= 30.48 cm 1 in= 2.54 cm

Common Units and their equivalents: Mass-

Mass 1 Kilogram (kg)= 2.205 pounds (lb) 1 pound (lb)= 453.59 grams (g) 1 ounce (oz)= 28.35 grams (g)

Common Units and their equivalents: Volume-

Volume 1 liter (L)= 1000 milliliters (mL) = 1000 cubic meters (cm^3) 1 liter (L)= 1.057 quarts (qt) 1 U.S gallon (gal)= 3.785 liters (L)

Density is

a fundamental property of a substance that relates the mass of that substance to its volume equivalent. And a temperature dependent physical property that is used to identify a substance

A conversion factor is

a numerical relationship between two different units that is used to multiply or divide a quantity to convert it from one system of units to another.

A derived unit is formed from other units using

a step- by -step process called "the Factor-label Method" OR "unit conversion" or "dimensional analysis".

A number without a unit...

has no meaning.

When converting numbers with units that are raised to a power...

the conversion factor must also be raised to that power for the units to cancel.

Science measurements are based on

the metric system units and are called SI units.