CONVERSION FACTORSObjective: Learn to use one or more conversion factors to solve rate problems.

CONVERSION FACTORWhat is a conversion factor?A conversion factor is a fraction

whose numerator and denominator represent the

same quaintly but use different units.

Thus the fraction is equal to 1.

EXAMPLE:

1 day

1 day

24 hours

1 day

RIGHT?

1 day

24 hours

RIGHT?

1440 minutes

24 hours

1440 minutes

86400 seconds

And so on…

US

EFU

L M

EA

SU

REM

EN

TS

How many do you know?

Conversionsinches (in) =1 foot (ft)

feet (ft) =1 yard (yd)

centimeters(cm)

=1 meter (m)

meters =1 kilometer (k)

ounces (oz) =1 pound (lb)

seconds(s) =1 min

minutes(min) =1 hour (hr)

hours (hrs) =1 day

12

3

100

1000

16

60

60

24

G-

LA

ND

1-gallon (gal)= 4-quarts (qt)=

8-pints (pt)= 16-cups (c)=

128 ounces (oz) 8oz=1 cup

HELP

FU

L

HIN

TS

:

The conversion factor:Must introduce the desired

unitMust cancel the original unit

so that the desired unit is all that remains

The original unit must be on the opposite side of the conversion fraction.

. *mi h h

exft mi ft

2

. **

mi mi miex

ft h ft h

desiredgiven desiredunit

givenunit unitunit

FIN

DIN

G

CO

NV

ER

SIO

N

FAC

TO

RS

A. feet to yardsThere are 3 feet in 1 yard. To convert feet to yards, multiply the number of feet by

B. pounds to ouncesThere are 16 ounces in 1 pound. To convert pounds to ounces, multiply the number of pounds by

Find the appropriate factor for each conversion.

1

3

yd

ft

16

1

oz

lbRemember we need the

units in the denominator to cancel.

TRY THIS!Find the appropriate factor for each conversion.A. Kilometers to centimeters

B. Inches to yards

C. Hours to weeks

1000 m

1 km100 cm

1 m

100000 cm

1 km

1 ft

12 in1 yd

3 ft 1 yd

36 in

1 day

24 hrs1 wk

7 days 1 wk

168 hrs

Multiply the number of km by

this

Multiply the number of in by this

Multiply the number of hrs by this

TRY THIS!A strobe lamp can be used to measure the speed of an object. The lamp flashes every . A camera records the object moving 7.5cm between flashes. How fast is the object moving in ?

1

1000s

ms

m distanceunit rate= =

s time

7.51

1000

cm

s 7.5 1000

1 1

cm

s

7500

1

cm

s

Now convert cm to m

7500

1

cm

s

1

100

m

cm

7500

100

m

s

75

1

m

s

The object is traveling 75m/s

EXAMPLE 1:Find the appropriate factor for each conversion.A. feet to yards

B. pounds to ounces

EXAMPLE 2: The average American uses 580 pounds of paper per year. Find the number of pounds of paper the average American uses per month, to the nearest tenth.

EXAMPLE 3: A strobe lamp can be used to

measure the speed of an object. The

lamp flashes every of a second. A

camera records the object moving

52 cm between flashes. How fast is

the object moving in m/s?

1

100