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poundal

What Is poundal?

A poundal is an old unit used to measure force. It belongs to the foot pound second system that uses feet for length, pounds for mass, and seconds for time. The poundal tells us how strong a push or pull is on an object.

Definition

In simple words, one poundal is the amount of force needed to speed up a 1 pound mass by 1 foot per second every second.

Written as a formula:

  • 1 poundal is the force that gives 1 pound of mass an acceleration of 1 foot per second squared.

In SI units, which most of the world uses today:

  • 1 poundal ≈ 0.1383 newton

History / Origin

The poundal was created in the 1800s for engineers who worked with the foot pound second system. At that time, people used the pound both as a mass and as a force, which caused confusion.

To fix this problem, some scientists and engineers suggested a new clear unit of force based on the pound of mass and feet per second squared. This new unit was called the poundal. It helped separate mass from force inside that system.

Later, the world slowly moved to the metric system that uses the newton as the main unit of force. Because of this, the poundal became less common and is now mainly of historical interest.

Symbol & Abbreviation

The poundal is usually written with the short form:

  • pdl for poundal

Examples:

  • 10 pdl means 10 poundals of force.
  • F = 25 pdl means the force F is 25 poundals.

Current Use Around the World

Today the poundal is rarely used. Most scientists, students, and engineers use the SI unit called the newton instead.

You may still see poundals in:

  • Older engineering books that use feet and pounds.
  • Historical documents about physics and engineering.
  • Some special classroom examples that compare unit systems.

Modern work in science, space, and most engineering uses newtons for force. In some US industries, people use pound force instead of poundal when they stay in the imperial style system.

Example Conversions

Here are useful conversion values between poundals and other force units.

Between poundal and newton

  • 1 pdl ≈ 0.1383 N
  • 1 N ≈ 7.233 pdl

Examples:

  • 5 pdl ≈ 5 × 0.1383 ≈ 0.6915 N
  • 20 pdl ≈ 20 × 0.1383 ≈ 2.766 N
  • 10 N ≈ 10 × 7.233 ≈ 72.33 pdl

Between poundal and pound force

Pound force is another unit of force in the imperial style system. At Earth gravity:

  • 1 pound force ≈ 32.174 pdl
  • 1 pdl ≈ 0.03108 pound force

Examples:

  • 100 pdl ≈ 100 × 0.03108 ≈ 3.108 pound force
  • 5 pound force ≈ 5 × 32.174 ≈ 160.87 pdl

These units are closely related to the poundal because they also measure force.

  • Newton (N) The main SI unit of force. 1 pdl ≈ 0.1383 N.
  • Pound force (lbf) A force unit still used in some US industries. 1 lbf ≈ 32.174 pdl.
  • Dyne The force unit in the older cgs system. 1 N = 100000 dyne, so 1 pdl ≈ 13825 dyne.
  • Kilogram force (kgf) A metric style force unit based on Earth gravity. 1 kgf ≈ 9.80665 N ≈ 71.94 pdl.

FAQs

What is a poundal in very simple words?

A poundal is a unit used to tell how strong a push or pull is when using feet and pounds. It is like the newton but in a different unit system.

How is a poundal defined in physics?

One poundal is the force that makes a 1 pound mass speed up by 1 foot per second every second. This is an acceleration of 1 foot per second squared.

Is the poundal still used today?

Only rarely. It mostly appears in old books and in teaching examples. Modern science uses the newton instead.

What is the symbol for poundal?

The common symbol for the poundal is pdl.

How do I convert poundal to newton?

Multiply the number of poundals by 0.1383.

  • Force in newtons = force in poundals × 0.1383

How do I convert newton to poundal?

Multiply the number of newtons by about 7.233.

  • Force in poundals = force in newtons × 7.233

What is the difference between poundal and pound force?

Poundal is defined from mass and acceleration. Pound force is based on how much gravity pulls on a 1 pound mass at Earth surface. At Earth gravity, 1 pound force is about 32.174 poundals.

Why did the poundal become unpopular?

The world moved to the SI system that uses meters, kilograms, and seconds. The newton became the standard unit of force, so there was little need to keep using the poundal.

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