The ratio between daN and kg: force and mass, what are the differences?
In the world of marine, construction and activities where safety and strength are crucial, measuring the strength of materials is essential. For this, the units daN (decanewton) and kg (kilogram) are often used to measure the load and strength of elements such as ropes, such as those made of Dyneema or HMPE, which must be able to withstand high tensions without risk. But what is the difference between these units, and how to interpret them? Let’s find out the relationship between daN and kg, and why these two units are so important.
The kilogram (kg): a unit of mass
The kilogram, denoted kg , is the International System of Units (SI) unit of mass. It is a measure of the amount of matter contained in an object, regardless of the force acting on it. When we say that an object has a mass of 1 kg, this simply means that it contains a certain amount of matter, without reference to gravity or any force acting on it.
However, in everyday life we perceive the kg as a unit of "weight" because we live on Earth, where gravity creates an attractive force that makes objects "weigh" something. This "weight" that we feel is actually a force resulting from the mass (in kg) multiplied by gravity (about 9.81 m/s²).
The decanewton (daN): a unit of force
The decanewton (daN) is a unit of force. It is used to quantify an exerted force, such as the tension of a rope, pressure, or mechanical effort. In the International System, force is expressed in newtons (N), and 1 decanewton = 10 newtons . One daN therefore corresponds to a force of 10 N.
Why is daN often used in comparison to N in practical areas, such as navigation or mountaineering? Simply because 1 daN represents a force equivalent to the weight of a 1 kg object under normal conditions of Earth's gravity. This makes it easier to interpret loads and forces without constant calculations, which is ideal for quick estimates.
The relationship between daN and kg: a practical approximation
On Earth, gravity exerts an acceleration of 9.81 m/s² on objects, which means that an object of 1 kg mass is subjected to a force of approximately 9.81 N (or 1 daN). This is why 1 daN is often rounded to 1 kg to simplify calculations. This approximation is particularly useful in situations where precision does not need to be extreme, such as when assessing the maximum loads that a rope can support.
For example, if a rope indicates a maximum strength of 500 daN, this means that it can withstand a load equivalent to approximately 500 kg under Earth's gravity. In reality, this is more precisely equivalent to 510 kg when taking into account the exact gravity (500 daN × 9.81 m/s²), but rounding is often sufficient for the majority of applications.
In conclusion
Understanding the relationship between daN and kg helps to better interpret the resistance and load values of equipment. The kilogram represents a fixed mass, while the daN measures a force. Due to the constant effect of Earth's gravity, 1 daN ≈ 1 kg is a commonly used approximation to simplify calculations in many industries, from navigation to construction. With this equivalence, it is easy to quickly estimate the load capacity of ropes or other safety equipment, ensuring safer and more reliable operations.