lectureplus timberlake1 chapter 1 measurements using conversion factors

LecturePLUS Timberlake 1

Chapter 1

Measurements

Using Conversion Factors


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 = _______


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)


Learning Check CF1

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

1) 2440 cm

2) 244 cm

3) 24.4 cm


Solution CF1

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


Learning Check CF2

How many seconds are in 1.4 days?

Unit plan: days hr min seconds

1.4 days x 24 hr x ??

1 day


Solution CF2

Unit plan: days hr min seconds

1.4 days x 24 hr x ??

1 day2 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


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


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


Learning Check CF3

An adult human has 4650 mL of blood. How many gallons of blood is that?Unit plan: mL qt gallon

Equalitites: 1 quart = 946 mL

1 gallon = 4 quarts

Your Setup:


Solution CF3

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


• List 4 or more things to remember when you are getting ready to work a problem.

• Compare your list with another student.

• Add to your list, if necessary.

Steps to Problem Solving


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


A friend needs to know the length of a ski pole in mm. The length is given in feet.

Write a short paragraph of 3 to 4 complete sentences describing how you would change from one unit to the other. (Don't use any numbers at this time.) Read your paragraph to a neighbor.


Learning Check CF4

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


Solution CF4

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

1 ft 1 in. 1 cm


Learning Check CF5

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?


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 CF5


Using Percent (%)

% = Parts x 100

Whole

% = Number (%) of Items x 100

100 Items


Percent (%) as a Conversion Factor

Select a unit (mass, volume, etc.)

Write the % value in the numerator

Write 100 of the same unit for the

denominator

= 25 unit of mass of sugar

100 unit of mass of candy


Example: A candy is 25% (by mass) sugar.

Select a unit of mass

in grams

25 g sugar and 100 g candy

100 g candy 25 g sugar

in milligrams

25 mg sugar and 100 mg candy

100 mg candy 25 mg sugar


Learning Check CF6

Sea water is 3.1%by mass salt (NaCl). Write the factors for the % using (1) kg and (2) lb

(1) _______________ and ______________

(2) _______________ and ______________


Solution CF6

Sea water is 3.1% salt (NaCl). Write

factors for % using (1) kg and (2) lb

(1) 3.1 kg NaCl and 100 kg sea water

100 kg sea water 3.1 kg NaCl

(2) 3.1 lb NaCl and 100 lb sea water

100 lb sea water 3.1 lb NaCl


Learning Check CF7

How many lb of sugar are in 120 g of candy if the candy is 25% (by mass) sugar?


Solution CF7

How many lb of sugar are in 120 g of candy if the candy is 25%(by mass) sugar?

% factor

120 g candy x 1 lb candy x 25 lb sugar

454 g candy 100 lb candy

= 0.067 lb sugar

lectureplus timberlake1 chapter 1 measurements using conversion factors

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