1. Ch. 4-2 Converting Units November 14, 1999
Most physics and chemistry textbooks start with a chapter dedicated to units, precision, and significant digits. You may discover that your science teacher will not accept a value as a correct answer if there are no units attached. The fate of NASA's $125 million Mars orbiter shows that teachers are not just being picky, they are practicing good science.
The Mars orbiter had completed a 9-month journey and on September 23 was ready to be placed in orbit around Mars. While the engineers sent signals to the orbiter to adjust its path, the spacecraft moved too close to the planet's atmosphere and broke into pieces or burned.
An investigation into the mishap discovered that one team of engineers working on the orbiter had used metric units while another team had used English units for a key spacecraft operation. Therefore, information did not transfer between the teams at the critical moment, and the orbiter was lost.

2. Do not write just understand
12 inches equal 1 foot
Do not write just understand

3. 1 ft = 1 12 in 1 mile = 1 5,280 ft 12 in. = 1 1 ft 5,280 ft = 1 1 mile
conversion factor
-Since conversion factors equal 1, multiplying by them does not change the value of a measurement.
a rate equal to 1
1 ft = 1
12 in
1 mile = 1
5,280 ft
12 in. = 1
1 ft
5,280 ft = 1
1 mile
1 m = 1
100 cm
100 cm = 1
1 m

4. Units of Measurement Type Unit Equivalent Length (customary) Inch Foot
-You will need to bring your conversion chart with you everywhere in order to do these problems. I do not expect you to memorize them even though you should know some of them!
Type
Unit
Equivalent
Length (customary)
Inch
Foot
Yard
Mile
1 ft. = 12 in.
1 yd. = 3 ft.
1 mi. = 5280 ft.
Length (metric)
Centimeter
Meter
Kilometer
1 m. = 100 cm.
1 km. = 1000 m.
Capacity (customary
Fluid ounce
Cup
Pint
Quart
Gallon
1 c. = 8 fl. Oz.
1 pt. = 2 c.
1 qt. = 2 pt.
1 gal. = 4 qt.
Capacity (metric)
Milliliter
Liter
1 L. = 1000 mL.

5. Customary Units and Metric Unit
Units of Measurement
Type
Unit
Equivalent
Weight (Customary)
Ounce
Pound
Ton
1 lb. = 16 oz.
1 t. = 2000 lb.
Mass (Metric)
Gram
Kilogram
1 kg. = 1000 g.
Type
Customary Units and Metric Unit
Length
1 in = 2.54 cm
1 mi ≈ 1.61 km
1 ft ≈ 0.3 m
Capacity
1 qt ≈ 0.94 L
Weight & Mass
1 oz ≈ 28.4 g
1 lb ≈ 0.45 kg

6. Example 1: Convert the following measurements below.
a.) 1.2 miles to feet b.) 32 in. to feet
= 6336 ft.
= 2.7 feet.
Example 2: Convert the following measurements below.
a.) 90 in./min. to ft./min. b.) 12 qt./min. to gal./min.
= 7.5 ft./min.
= 3 gal./min.

7. Example 3: Convert the following measurements below.
a.) 12 mi / hr to yd. / min.
b.) 0.6 mi / hr to in / sec

8. Homework Pg. 169 # 1-6 all do in one square # 8-12 even,
20-24 even only
Practice Sheet 4.2
#1-16 evens only
Ec for any others