(FOM) Types of Forces Lesson
Types of Forces
All forces can be placed into two basic categories: distant forces and contact forces. As you can imagine, contact forces are those forces in which the interacting objects have some sort of physical contact. Distant forces, on the other hand, are those forces in which the two interacting objects do not have physical contact but are still pushing or pulling on each other at a distance.
Distant Forces
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Force |
Definition |
|---|---|
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Gravitational Force Fg |
Gravity is a force that attracts objects toward other massively large objects such as the Earth or the moon. On Earth, all objects experience a downward force due to gravity to the center of the Earth. |
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Electromagnetic Force
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A force that acts between charged particles and is the combination of all electrical and magnetic forces. The electromagnetic force can be attractive or repulsive. |
Contact Forces
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Force |
Definition |
|---|---|
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Applied Force Fapp |
An applied force is a force applied by another object such as a person, machine, and lots of others. For example, if you push a book across a table then you are applying a force with your hand to push the book. |
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Normal Force Fn |
Also called the support force because it supports the weight of an object on a surface. For example, the table supports a book resting on a table. |
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Friction Force Ff |
A force that opposes the motion of an object caused by the force exerted by the surface as an object moves across it. There are three types of frictional forces: sliding friction, rolling friction, and static friction. Sliding friction occurs when one solid surface slides over another solid surface. Rolling friction occurs when an object rolls across a solid surface. Static friction occurs between the surfaces of two objects that touch but do not move against each other. Static friction must be overcome for one of the objects to move. |
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Air Resistance Force Fair |
A type of frictional force that opposes the motion of an object as it moves through the air. For example, if a book fell off a table then gravity would be pulling it down and air resistance would be pushing slightly up on the book. |
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Tension Force Ftens |
A force that is transmitted through a string, rope, cable, or wire when it is pulled tight by forces acting from opposite ends. |
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Spring Force Fspring |
A force exerted by a compressed or stretched spring upon any object that is attached to it. An object that compresses or stretches a spring is always acted upon by a force that restores the object to its rest or equilibrium position. |
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