Unit of Length

Unit of Length is the measurement of the length of an object. The most common units used today are metric units. The SI unit of length is meter. Other units of length include inch, mile, centimeter, kilometer, etc.

In this article, we will learn about unit of length, SI unit of length, unit of length in other systems along with some practice questions based on it.

What is Length?

Length refers to the measurement of distance from one point to another, whether in physical dimensions (height, width), spatial measurements (meters, feet), or time duration (length of a movie, meeting).

The measurement of an object from one end to other is referred to as length.

Length is a fundamental concept in geometry and physics, denoting the extent of an object.

What is Unit of Length?

Unit of length is a common way to measure the size of a one-dimensional object. The meter (m) is the basic unit of length in the International System of Units (SI).

Other units that are often used for smaller and bigger measurements, respectively, include centimeters (cm) and kilometers (km), which are derived from the meter.

Unit of Length Definition

A standardized measurement used to express the length of a one-dimensional object or the separation between two points is called a unit of length.

SI unit of length is meter. Other common units used to measure length of an object include mile, inch, centimeter, etc.

Measurement of Length

Length is the measurement of how long an object is. Length is divided into two types:

• Long distance Length
• Short distance Length

The distance of the length determines which unit and tools are used for its measurement.

Measuring Long Distance Lengths

Depending on the scale of the measurement, measuring great distances such as distance between earth and sun, usually requires the use of the proper tools and units. Here are a few typical techniques:

• Surveying Tools: To precisely measure large distances across landscapes, professional surveyors employ tools like GPS (Global Positioning System) devices are used. These instruments offer accurate measurements for building and mapping tasks.

• Measurement Wheels: Surveyor’s wheels, clickwheels, and measuring wheels are similar devices that move along the ground with a wheel. They can be used for measurements outside because the wheel’s revolution is translated into distance measurements.

• GIS and satellite imagery: Large-scale distance measurements are made using satellite photography and geographic information systems (GIS). These technologies offer precise and comprehensive data for analysis and mapping.

Measuring Short Distance Lengths

Short distances can be measured with a variety of basic instruments and units. The following are typical techniques for measuring close distances:

• Rulers and Measures with Tape: Rulers and tape measures are useful instruments for small-scale measurements. Straight and curved surfaces can be measured with tape measures; rulers are usually measured in inches or centimeters.

• Calipers: Calipers are high-precision instruments used to measure small distances precisely. They are available in numerous varieties, such as digital and vernier calipers, that are appropriate for diverse uses.

• Tools for Digital Distance Measuring: Short-range measurements can be made quickly and accurately with digital measuring devices like laser distance meters. They are especially helpful for projects involving building and home renovation.

• Steps and Pacing: Short distances can be roughly estimated by counting footfall or pacing. On the other hand, this approach is not as exact as employing accurate measuring instruments.

SI unit of Length

In the International System of Units (SI), which is the modern form of the metric system and the globally accepted system of measurement, the primary unit of length is the meter (m).

SI unit of length is the meter (m).

The unit meter is a fundamental unit of measurement for length, and it is used in many aspects of our daily lives, from measuring distances to constructing buildings to conducting scientific research.

Here are some other scientific units of length in the SI system:

1. Meter (m):
   • The meter is the base unit of length in the SI system. It is defined as the distance that light travels in a vacuum in 1/299,792,458 seconds.
2. Kilometer (km):
   • The kilometer is equal to 1,000 meters. It is commonly used for longer distances, such as measuring the length of roads, distances between cities, or geographical features.
3. Centimeter (cm):
   • The centimeter is equal to 0.01 meters or one hundredth of a meter. It is often used for smaller measurements, such as the height of a person or the dimensions of objects.
4. Millimeter (mm):
   • The millimeter is equal to 0.001 meters or one thousandth of a meter. It is frequently used in precision measurements, especially in fields like engineering and biology.
5. Micrometer (μm):
   • The micrometer, also known as a micron, is equal to 0.000001 meters or one millionth of a meter. It is commonly used in scientific and technological contexts, particularly in microscopy.
6. Nanometer (nm):
   • The nanometer is equal to 0.000000001 meters or one billionth of a meter. It is commonly used in fields such as nanotechnology and molecular biology.

CGS Unit of Length

The fundamental units of length, mass, and time in the CGS system are centimeters, grams, and seconds, respectively. Therefore, centimeter (cm) is the fundamental unit of length in the CGS (centimeter-gram-second) system of units.

Since the centimeter is one tenth of a meter, it is a smaller unit that can be used in lab settings or to measure lengths.

Conversion of Unit of Length

Here is a simple tabular representation for the conversion of units of length within the metric system:

Unit	Symbol	Equivalent to 1 Meter
Kilometer (km)	km	1 km = 1,000 meters
Hectometer (hm)	hm	1 hm = 100 meters
Decameter (dam)	dam	1 dam = 10 meters
Meter (m)	m	1 meter = 1 meter
Decimeter (dm)	dm	1 dm = 0.1 meters
Centimeter (cm)	cm	1 cm = 0.01 meters
Millimeter (mm)	mm	1 mm = 0.001 meters

This table shows the relationship between various metric units of length and their equivalents in meters. To convert between these units, you can use the relationships provided in the table.

For example, to convert from centimeters to meters, divide the number of centimeters by 100, or to convert from kilometers to meters, multiply the number of kilometers by 1,000.

Other Non-SI Units of Length

There are various non-SI (International System of Units) units of length include:

• Inch (in): Commonly used in the United States and some other countries for measuring short distances and dimensions. One inch is equal to 0.0254 meters.

• Foot (ft): Often used in the United States and the United Kingdom for measuring height and distance. One foot is equal to 0.3048 meters.

• Yard (yd): Commonly used in the United States and the United Kingdom for longer measurements. One yard is equal to 0.9144 meters.

• Mile (mi): Frequently used in the United States for measuring longer distances. One mile is equal to 1.60934 kilometers.

• Nautical Mile (nmi or NM): Used in navigation and aviation. One nautical mile is defined as one minute of latitude and is approximately equal to 1.852 kilometers.

• Angstrom (Å): Commonly used in the field of molecular biology and chemistry to express atomic and molecular distances. One angstrom is equal to 0.1 nanometers or 1 × 10^-10 meters.

• Fathom (fth): Primarily used in navigation for measuring the depth of water. One fathom is equal to 1.8288 meters or 6 feet.

• League: Historically used for measuring distances at sea or on land. The league has varied in size, but it is often considered equivalent to three nautical miles.

Read More,

• Unit of Power
• Unit of Mass
• Unit of Distance

Solved Examples on Unit of Length

Example 1: Convert 150 m to cm.

Solution:

We know that 1m = 100 cm

Hence, 150 m = 150 × 100 = 15000 cm

Therefore, 150 m is equal to 15000 cm.

Example 2: A box has length of 200 cm and another box has length of 2.5 m. Which box has more length?

Solution:

Length of first box = 200 cm

Length of second box = 2.5 m = 2.5 × 100 cm = 250 cm

As 250 > 200

Therefore, length of second box is greater than length of first box

Practice Questions on Unit of Length

Here are some practice questions related to the unit of length:

Question 1: Convert 3.5 kilometers to meters.

Question 2: Express 0.0024 meters in millimeters.

Question 3: If a room is 5.8 meters long, 3.2 meters wide, and 2.5 meters high, what is its volume in cubic meters?

Question 4: Which is larger: 1.2 kilometers or 1800 meters?

Question 5: Write 7.45 x 10⁴ meters in standard decimal notation.

FAQs on Unit of Length

What is the unit of length?

The unit of length is called the meter (m). It is the base unit of length in the International System of Units (SI) .

What is the smallest unit of length?

The smallest unit of length in the International System of Units (SI) is the Planck length, denoted by l_P.​

What is the biggest unit of length?

The biggest unit of length is the light-year (ly). 1 light-year = 9.461 × 10¹⁵ meters, or 9.461 × 10¹² kilometers.

What is the basic unit of length?

The basic unit of length is the meter (m).

What is the unit of measurement for length?

The unit of measurement for length in the International System of Units (SI) is the meter, abbreviated as “m.”

What are the 7 units of length?

The seven units of length include the meter (m), kilometer (km), centimeter (cm), millimeter (mm), micrometer (μm), nanometer (nm), and picometer (pm).