What is the longest length: one yard, one kilometer, one meter, or one inch?
The longest length out of the given options is one kilometer.
To determine which unit of length is the longest, we need to compare the given options: one yard, one kilometer, one meter, or one inch.
To start, let's convert all the units of length to a common unit, such as meters, which is the base unit in the International System of Units (SI).
1 yard is equal to 0.9144 meters. (Note: 1 meter is defined as the length of the path traveled by light in a vacuum in 1/299,792,458 of a second.)
1 kilometer is equal to 1,000 meters. (Note: "kilo" means a thousand in the metric system.)
1 meter is equal to 1 meter.
1 inch is equal to 0.0254 meters. (Note: 1 inch is defined as exactly 2.54 centimeters.)
Now that we have converted all the units to meters, we can see that:
1 yard = 0.9144 meters
1 kilometer = 1,000 meters
1 meter = 1 meter
1 inch = 0.0254 meters
Comparing these values, we can conclude that one kilometer is the longest length among the given options since it is equal to 1,000 meters.