1
Period 1 Activity Sheet Solutions:
Intro to the World of Energy
1.1
What Are Ratios? How Are They Used?
Your instructor will introduce the concepts of ratios and “per.”
Use this information to
answer the questions in this section.
a)
Ratios are useful when making comparisons.
Use ratios to compare the number
of miles each vehicle can travel using one gallon of gas.
1)
A sports car uses 0.8 gallons of gas to travel 17
miles.
How many miles per gallon does it get?
17 miles
=
21 miles/gal
0.8 gal
2)
A sports utility vehicle uses 3.9 gallons to gas to travel
57 miles.
How many miles per gallon does it get?
57 miles
=
15 miles/gal
3.9 gal
3)
How many gallons of gas does the sports car require to travel 243 miles?
243 miles
x
1 gal
=
12 gal
21 miles
b)
The next activity illustrates how ratios are used to convert units.
1)
Using the blue balances on your table, place washers in the center of
one balance pan and plastic chips in the center of the other pan.
a)
How many chips are required to balance one washer?
__
9
__
b)
Write the number of chips per washer as a ratio.
_
9
chips/1 washer
_
2)
Using the balance, find how many chips are required to balance one
metal nut. Write the number of chips per nut as a ratio.
_3 chips/1 nut
_
3)
Without using the balance
, calculate how many nuts there are per washer.
Show the steps in your calculation, including units and how they cancel.
9 chips
x
1 nut
=
9 nuts
=
3 nuts
1 washer
3 chips
3 washers
1 washer
_
3 nuts/washer
_
4)
Use the balance to check your answer to part c.
How many nuts balance one
washer? _
3
_
c)
Use ratios to convert 10 miles/1 gallon of gas into kilometers/liter.
Show the
steps in the calculation, including units and how they cancel.
(Hint:
1 mile =
1.609 kilometers and 1 gallon = 3.785 liters.)
10 mi
x
1.609 km
x
1 gal
=
16.09 km
=
4.251 km
1gal
1 mi
3.785 l
3.785 l
1 liter
d)
Group Discussion Question: List some common ratios.
Why are ratios useful?
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 Spring '10
 Staff
 Scientific Notation, Energy, Kilogram, Gallon, Group Discussion Question

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