Kilometer
A kilometer (km) is a unit of length in the metric system, used to measure long distances. One kilometer equals 1,000 meters or about 0.62 miles. Kilometers are commonly used to measure distances between cities, in road signs, and in running or walking events. For example, a marathon is 42.195 kilometers long. The symbol for kilometer is "km". Most countries around the world use kilometers instead of miles for speed and distance, especially in transportation. Because it covers a large distance, the kilometer is not used for measuring small objects but is perfect for travel and mapping.
Planck Length
The Planck length is the smallest meaningful unit of length in physics, representing a fundamental scale at which classical ideas about gravity and space-time break down and quantum effects dominate.
It is defined as approximately 1.616 × 10⁻³⁵ meters.
The Planck length is derived from fundamental constants: the speed of light, Planck’s constant, and the gravitational constant.
It sets a theoretical limit below which the very concepts of space and distance may lose conventional meaning.
Used mainly in theories of quantum gravity and string theory.
Key facts:
1 Planck length ≈ 1.616 × 10⁻³⁵ m
Smallest scale in quantum physics and cosmology
Represents a scale where quantum effects of gravity become significant
The Planck length is crucial for understanding the fabric of the universe at its most fundamental level.
No conversions available for length.