Per1_over

# Per1_over - Introduction to the World of Energy 1.1 Ratios...

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Introduction to the World of Energy 1.1 Ratios and “per” How can ratios simplify problem solving? How are ratios used to find efficiency? 1.2 Exponents and Scientific Notation Why is scientific notation helpful? How does it work? 1.3 Energy Sources How much energy do equal amounts of fuel contain? 1.4 Linear and Exponential Growth What are the differences between linear and exponential growth rates? How do graphs illustrate these rates? 1-1

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Activity 1.1.a: Ratios and “per” Ratios are fractions, such as 60 miles/1hour (60 miles per hour) Ratios are useful when making comparisons. Example: A truck requires 3 liters of gasoline to travel 15 kilometers. How many kilometers can the truck go on 1 liter of gas? Solution: Write the information as a ratio. Simplify the ratio by dividing the numerator by the denominator. 15 km = 5 km 3 liters liter 1-2
Activity 1.1.c: Ratios and Units How can ratios help solve problems? Ratios can be used to convert quantities from one unit to another. (For example miles per hour to meters per second.) The equality 1 hour = 60 min can be written: 1 hour or 60 min 60 min 1 hour Choose the ratio that allows you to cancel the unwanted units. Convert 60 miles/1hour into miles/minute: (Example 1.3) There are 1,609 meters per 1 mile. Use ratios to convert 60 miles per hour into meters per second. sec 1 meters 27 sec 60 min 1 x min 60 hour 1 x mile 1 meters 609 , 1 x hour 1 miles 60 = min 1 mile 1 min 60 miles 60 min 60 hour 1 x hour 1 miles 60 = = 1-3

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Act 1.1.d: Uses of Ratios Ratios often involve the amount of a quantity per unit of time: Miles / hour Heart beats / minute Other common ratios involve the cost of an item per unit of the item. Cost of gasoline / gallon Cost of electricity / kilowatt hour Ratios allow us to make comparisons more easily. By looking at the first two rows of data in the table, you cannot easily determine which vehicle gets the best gas mileage. Type of vehicle Minivan School Bus Truck Miles driven 218 1,089 37 Gas used 15 gal 85 gal 2.8 gal Miles per gal When you use a ratio to calculate the miles per gallon, the comparison is simple. 1-4
Act 1.2: Using Ratios to Find Efficiency Efficiency is a ratio of the useful energy out of the system per total energy put into the system.

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Per1_over - Introduction to the World of Energy 1.1 Ratios...

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