Chapter 1 Measurements

1
Chapter 1Measurements

• Using Conversion Factors

2
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 18C, how many
  ounces of blood would that be?
• Initial pints Final unit _______

3
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)

4
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

5
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

6
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

7
Solution CF2

• Unit plan days hr min
  seconds
• 1.4 days x 24 hr x ??
• 1 day
• 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

8
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

9
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

10
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

11
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

12
Steps to Problem Solving

• 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.

13
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

14

• 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.

15
Learning Check CF4

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

16
Solution CF4

• 3.0 ft x 12 in x 2.54 cm x 10 mm
• 1 ft 1 in.
  1 cm

17
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?

18
Solution CF5

• 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 min final (2 SF)

19
Using Percent ()

• Parts x 100
• Whole
• Number () of Items x 100
• 100 Items

20
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

21

• 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

22
Learning Check CF6

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

23
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

24
Learning Check CF7

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

25
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