What unit do scientists use to measure force?

Force is a fundamental concept in physics that describes the interaction between objects. When one object exerts a force on another object, it can result in the acceleration, deceleration, or deformation of the object. To quantitatively measure and analyze force, scientists use specific units.

What unit do scientists use to measure force?

The unit of force in the International System of Units (SI) is the Newton, abbreviated as “N”. A Newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared. Mathematically, this relationship is expressed by Newton’s second law of motion:

\[
F = ma
\]

Where \( F \) is the force in Newtons, \( m \) is the mass in kilograms, and \( a \) is the acceleration in meters per second squared.

In the British Imperial System, the unit used to measure force is the pound-force, denoted as “lbf.”

Newton (N)

Newton is the SI unit of force, defined as the force required to accelerate a one-kilogram mass by one meter per second squared (\(F=ma\)).

Pound-Force (lbf)

Pound-force is a unit of force used in the Imperial system, defined as the force exerted by one pound of mass in the gravitational field of Earth.

\[
1 \text{ lbf} = 4.448 \text{ N}
\]

Conversion Between Units

To convert between these units, the following conversion factor is commonly used:

\[
1 \text{ N} = 0.2248 \text{ lbf}
\]

Or conversely,

\[
1 \text{ lbf} = 4.448 \text{ N}
\]

You can convert from lbf to N using the formula \( F_{\text{N}} = 4.448 \times F_{\text{lbf}} \).

Other Units and Systems

In addition to Newton, pound-force, and dyne, there are other units for measuring force that are less commonly used or are applied in specialized contexts.

Kip

The kip is an American unit of force that equals 1,000 pound-forces. It is often used in civil and mechanical engineering for structural load calculations.

\[
1 \text{ kip} = 1000 \text{ lbf} = 4448.22 \text{ N}
\]

Poundal

The poundal is a unit in the foot-pound-second (FPS) system, commonly used in the United Kingdom. It is defined as the force necessary to accelerate a one-pound mass by one foot per second squared.

\[
1 \text{ poundal} = 0.138255 \text{ N}
\]

Ton-Force

In industrial contexts, force may be measured in tons-force, either metric or short tons, to describe large forces such as those exerted by hydraulic systems or machinery.

\[
1 \text{ metric ton-force} = 9806.65 \text{ N}
\]
\[
1 \text{ short ton-force} = 8896.44 \text{ N}
\]

Sthène

The sthène is a metric unit of force used in the field of gravimetry for measuring large forces. It is not an SI unit but is accepted for use with SI units.

\[
1 \text{ sthène} = 1000 \text{ N}
\]

Table of Units for Measuring Force and Their Conversion to SI Units

Below is a table that lists various units for measuring force and their conversion factors to the SI unit of force, which is the Newton (N).

Unit	Abbreviation	Conversion to Newton (N)	Formula to Convert to Newtons (N)
Newton	N	1 N	\(1 \text{ N} = 1 \text{ N}\)
Pound-Force	lbf	4.448 N	\(1 \text{ lbf} = 4.448 \text{ N}\)
Dyne	dyn	\(1 \times 10^{-5}\) N	\(1 \text{ dyn} = 1 \times 10^{-5} \text{ N}\)
Kip	kip	4448.22 N	\(1 \text{ kip} = 4448.22 \text{ N}\)
Poundal	pdl	0.138255 N	\(1 \text{ pdl} = 0.138255 \text{ N}\)
Metric Ton-Force	tf (metric)	9806.65 N	\(1 \text{ tf (metric)} = 9806.65 \text{ N}\)
Short Ton-Force	tf (short)	8896.44 N	\(1 \text{ tf (short)} = 8896.44 \text{ N}\)
Sthène	sn	1000 N	\(1 \text{ sn} = 1000 \text{ N}\)
Kilogram-Force	kgf	9.80665 N	\(1 \text{ kgf} = 9.80665 \text{ N}\)