30
Use of Dimensions
SOLUTION:
To find the number of feet, we need the product shown in the equation
ft
feet = 1 5 nrt x 5280 —
vert
= 7920 ft
Alternatively, we may use the solution
feet = 1 5 jot x 5280 ft mi'
1
= 7920 ft
PROBLEM:
Find the number of gallons in 5 cu yd (also written as yd
3 ), using the conversion
factors
231 in
3 = 1 gal
3 ft = 1 yd
12 in = 1 ft
SOLUTION:
gallons = 5 yd
3 x (3 -7) x (12
l -^\ yd/
\ it,
3
1 gal
x —-—
231 in
3
*
231;**
= 1010 gal
PROBLEM:
Find a conversion factor F by which you can convert yd
3 to gallons
SOLUTION:
A conversion factor can be developed from other known factors by calculating a
value of F that will satisfy the equation
gal = (yd)
3 [F]
F must have such units that, when they are substituted in this equation, they will
cancel yd
3 and yield only gal as the net result, as follows
= 202