Another common conversion between measurement systems deals with mass and weight. Mass is the amount of matter that an object contains, and weight is the force exerted on this amount of matter by gravity. Customary units describe an object’s weight, and metric/SI units describe an object’s mass. Weight and mass conversions occur in fields such as medicine, construction, and shipping, especially since these fields tend to cross international boundaries quite frequently. In order to convert between systems, you must first identify key units of measurement for mass and weight in each measurement system.

Copy the table below into your notes.

Fill in the chart below for customary units. Click on the blanks to check your answers.

Copy the table below into your notes.

Fill in the chart below for metric units. Click on the blanks to check your answers.

There are two important conversion facts that can be used to convert mass and weight between systems: 1 pound (lb) = 454 grams (g) and 1 kilogram (kg) = 2.2 pounds (lbs).

Source: Ferrari 458 Italia, Aurélien Vialatte, Wikimedia

To use these facts in a problem situation, consider the following report.

In September 2009, the car manufacturer Ferrari introduced the Ferrari 458 Italia sports car. The engineering and specifications of this machine were impressive to sports car fans, but since it was a European model, its mass is reported as 1,485 kg. What is the weight of this sports car in pounds?

First, make a plan for converting the units from kilograms to pounds.

Interactive popup. Assistance may be required. Click here to see a possible answer. Use dimensional analysis to convert kilograms to pounds.

Click on the image below to access the applet. Use the applet to perform dimensional analysis in order to perform the conversion.

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Pause and Reflect

Why is it important to be able to convert weight in pounds to mass in kilograms or vice versa?

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As goods and products are shipped from other countries into the United States, customs agents must be able to convert mass in kilograms to weight in pounds before the items can be allowed to enter the United States. Travelers need to know how to convert weight in pounds to mass in kilograms so that they know their luggage does not exceed weight limits when returning to the United States.

Practice

Source: Segway Tour, toooooool, Wikimedia

1. Hector is visiting Walt Disney World from a country that uses the metric system. He has elected to take a Segway Tour of the park. One of the restrictions of the Segway Tour is that each operator of the Segway must weigh less than 250 pounds. Hector knows he weighs 65.3 kilograms. Will he be able to take the Segway Tour?
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   Convert Hector’s weight from kilograms to pounds, and determine if it is within the 250 pound limit.
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2. A load zoned bridge has a weight limit of 6,000 pounds. A truck carrying cargo from Central America weighs 5,200 pounds. The cargo is a set of 18 boxes that each weighs 20.8 kilograms. Can the truck with all of its cargo safely pass over the load zoned bridge?
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   Determine the total weight of the cargo in kilograms, convert it to pounds, and add it to the weight of the truck.
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