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Explanation of Units of Force by Ron Kurtus - Succeed in Understanding Physics. Also refer to newton, metric, SI, measurement, dyne, poundal, physical science, School for Champions. Copyright © Restrictions
Units of Force
by Ron Kurtus (20 June 2009)
A force is an entity that acts on an object to change its velocity or direction. A unit of force is an arbitrary measurement that we designate as "1" (unit), so that all other measurements of force are multiples of that unit.
Most often, force is designated as a newton (N) in the metric or SI system of measurement. The newton has applications in various scientific measurements. There are other units, not used as often.
Questions you may have include:
- What is the definition of the newton?
- What are some applications of the newton?
- what are other units of force?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
Useful tools: Metric-English Conversion | Scientific Calculator.
Definition of newton
A newton is the force required to give a mass of 1 kilogram (1 kg) an acceleration of 1 meter per second per second (1 m/s2). It is abbreviated as N.
This unit of measurement is in the metric or SI system and is used in scientific work more than other units of force.
1 N is equivalent to 1 kg-m/s2.
Applications of the newton
The newton combined with other measurements is used in various applications.
Moment of force
The unit of torque or moment of force is the newton-meter (N-m), where m is the moment arm.
Energy, work and heat
The newton-meter (N-m) is also the definition of the joule (J), which is a unit of energy. It can be seen that the units of kinetic energy E = ½mv2 are in kilogram-meter2/seconds2 and kg-m2/s2 = N-m.
Power and radiant flux
Power is energy per second or N-m/s, with the unit of watt. This is also the unit for radiant flux or power from electromagnetic radiation.
Pressure
The unit of pressure is the pascal (P), which is the force per unit area (N-m2).
Other units of force
There are other units of force, not as commonly used as the newton.
Dyne
A dyne is the force required to give a mass of 1 gram (1 g) an acceleration of 1 centimeter per second per second (1 cm/s2). 1 N = 100,000 dynes.
You might use the dyne, if working with small objects.
Poundal and pound
A poundal is the force required to give a mass of 1 pound (1 lb) an acceleration of 1 foot per second per second (1 ft/s2). 1 poundal equals 0.1382 newtons.
A pound is the force applied on a mass of 1 pound (1 lb) by the acceleration due to gravity. It is a non-technical unit of force and is also called the weight.
These units of force are in the English system and are seldom used in scientific measurements.
Summary
A force acts on an object to change its velocity or direction. In most scientific work, force is designated as a newton (N) in the metric or SI system of measurement. The newton has applications in various scientific measurements. There are other units, not used as often.
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Resources and references
The following resources provide information on this subject:
Websites
Books
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books on Physical Science
Mini-quiz to check your understanding
If you got all three correct, you are on your way to becoming a Champion in Physics. If you had problems, you had better look over the material again.
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Units of Force