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Chapter 1

Measurements

Problem Solving fsUsing Conversion Factors

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Initial and Final Units

1. A person has a height of 2.0 meters. What is

that height in inches?

Initial unit = m Final unit = _______

2) Blood has a density of 0.05 g/mL. If a person

lost 0.30 pints of blood at 18°C, how many

ounces of blood would that be?

Initial = pints Final unit = _______

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How many minutes are in 2.5 hours?

Initial unit

2.5 hr

Conversion Final

factor unit

2.5 hr x 60 min = 150 min

1 hr

cancel Answer (2 SF)

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Learning Check

A rattlesnake is 2.44 m long. How long is the snake in cm?

1) 2440 cm

2) 244 cm

3) 24.4 cm

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Solution

A rattlesnake is 2.44 m long. How long is the snake in cm?

2) 244 cm

2.44 m x 100 cm = 244 cm

1 m

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Learning Check

How many seconds are in 1.4 days?

Unit plan: days hr min seconds

1.4 days x 24 hr x ??

1 day

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Solution CF2

Unit plan: days hr min seconds

2 SF Exact

1.4 day x 24 hr x 60 min x 60 sec

1 day 1 hr 1 min

= 1.2 x 105 sec

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Unit Check

What is wrong with the following setup?

1.4 day x 1 day x 60 min x 60 sec

24 hr 1 hr 1 min

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Unit Check

1.4 day x 1 day x 60 min x 60 sec

24 hr 1 hr 1 min

Units = day2/hr2 Not the final unit needed

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Learning Check An adult human has 4650 mL of blood. How many gallons of blood is that?

Unit plan: mL qt gallon

Equalities: 1 quart = 946 mL

1 gallon = 4 quarts

Your Setup:

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Solution

Unit plan: mL qt gallon

Setup:

4650 mL x 1 qt x 1 gal = 1.23 gal

946 mL 4 qt

3 SF 3 SF exact 3 SF

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Steps to Problem Solving

Read problem Identify data Write down a unit plan from the initial unit

to the desired unit Select conversion factors Change initial unit to desired unit Cancel units and check Do math on calculator Give an answer using significant figures

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Learning Check

If the ski pole is 3.0 feet in length, how long is the ski pole in mm?

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Solution

3.0 ft x 12 in x 2.54 cm x 10 mm =

1 ft 1 in. 1 cm

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Learning Check

If your pace on a treadmill is 65 meters per minute, how many seconds will it take for you to walk a distance of 8450 feet?

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Initial

8450 ft x 12 in. x 2.54 cm x 1 m

1 ft 1 in. 100 cm

x 1 min x 60 sec = 2400 sec

65 m 1 minfinal (2 SF)

Solution