Can The Magnitude Of The Force Exerted By An Inanimate Object Change

Types of Forces

A force is a push button or pull acting upon an object as a consequence of its interaction with another object. There are a multifariousness of types of forces. Previously in this lesson, a variety of force types were placed into ii broad category headings on the basis of whether the force resulted from the contact or non-contact of the ii interacting objects.

Contact Forces	Action-at-a-Distance Forces
Frictional Forcefulness	Gravitational Force
Tension Force	Electrical Force
Normal Force	Magnetic Force
Air Resistance Strength
Applied Force
Leap Force

These types of individual forces will now be discussed in more detail. To read about each force listed to a higher place, continue scrolling through this folio. Or to read virtually an individual strength, click on its proper noun from the list below.

Applied Forcefulness
Gravitational Force
Normal Strength
Frictional Force
Air Resistance Force
Tension Force
Bound Force

Blazon of Forcefulness (and Symbol)	Description of Force
Applied Force F_app	An applied strength is a force that is practical to an object past a person or another object. If a person is pushing a desk across the room, and so there is an applied force acting upon the object. The applied forcefulness is the force exerted on the desk-bound by the person. Render to Meridian
Gravity Force (as well known every bit Weight) F_grav	The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. Past definition, this is the weight of the object. All objects upon earth feel a strength of gravity that is directed "down" towards the center of the earth. The strength of gravity on earth is e'er equal to the weight of the object as institute by the equation: *Fgrav = chiliad chiliad** where grand = 9.eight Due north/kg (on Globe) and m = mass (in kg) (Caution: do non confuse weight with mass.) Return to Elevation
Normal Force F_norm	The normal force is the support force exerted upon an object that is in contact with another stable object. For example, if a book is resting upon a surface, then the surface is exerting an upward strength upon the volume in social club to support the weight of the book. On occasions, a normal forcefulness is exerted horizontally betwixt two objects that are in contact with each other. For instance, if a person leans against a wall, the wall pushes horizontally on the person. Render to Acme
Friction Force F_frict	The friction forcefulness is the force exerted by a surface as an object moves beyond it or makes an effort to move beyond information technology. There are at least 2 types of friction force - sliding and static friction. Though it is non e'er the instance, the friction force often opposes the movement of an object. For example, if a book slides across the surface of a desk, and so the desk exerts a friction force in the opposite management of its motion. Friction results from the 2 surfaces being pressed together closely, causing intermolecular bonny forces between molecules of unlike surfaces. Equally such, friction depends upon the nature of the two surfaces and upon the caste to which they are pressed together. The maximum amount of friction force that a surface can exert upon an object can be calculated using the formula below: F_frict = µ • F_norm The friction force is discussed in more particular later on this folio. Return to Peak
Air Resistance Force F_air	The air resistance is a special type of frictional strength that acts upon objects equally they travel through the air. The force of air resistance is often observed to oppose the motion of an object. This forcefulness will often be neglected due to its negligible magnitude (and due to the fact that it is mathematically hard to predict its value). Information technology is almost noticeable for objects that travel at high speeds (e.g., a skydiver or a downhill skier) or for objects with large surface areas. Air resistance will be discussed in more detail in Lesson 3. Return to Elevation
Tension Force F_tens	The tension force is the force that is transmitted through a string, rope, cablevision or wire when it is pulled tight by forces acting from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire. Return to Pinnacle
Leap Forcefulness F_spring	The spring force is the strength 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 past a force that restores the object to its rest or equilibrium position. For nigh springs (specifically, for those that are said to obey "Hooke's Law"), the magnitude of the force is straight proportional to the corporeality of stretch or pinch of the spring. Render to Height

Confusion of Mass and Weight

A few further comments should be added nearly the single strength that is a source of much defoliation to many students of physics - the forcefulness of gravity. Equally mentioned above, the forcefulness of gravity acting upon an object is sometimes referred to as the weight of the object. Many students of physics confuse weight with mass. The mass of an object refers to the amount of thing that is contained past the object; the weight of an object is the force of gravity interim upon that object. Mass is related to how much stuff is there and weight is related to the pull of the Earth (or any other planet) upon that stuff. The mass of an object (measured in kg) will be the same no matter where in the universe that object is located. Mass is never altered past location, the pull of gravity, speed or even the existence of other forces. For example, a 2-kg object will take a mass of 2 kg whether it is located on Earth, the moon, or Jupiter; its mass volition be 2 kg whether it is moving or non (at least for purposes of our study); and its mass will be ii kg whether it is being pushed upon or not.

On the other hand, the weight of an object (measured in Newton) volition vary according to where in the universe the object is. Weight depends upon which planet is exerting the forcefulness and the distance the object is from the planet. Weight, being equivalent to the force of gravity, is dependent upon the value of yard - the gravitational field strength. On earth's surface chiliad is ix.8 N/kg (oft approximated as ten N/kg). On the moon'south surface, 1000 is 1.7 N/kg. Get to another planet, and in that location volition be another g value. Furthermore, the 1000 value is inversely proportional to the distance from the center of the planet. Then if we were to measure out g at a distance of 400 km above the earth's surface, and then we would observe the g value to exist less than 9.eight Northward/kg. (The nature of the force of gravity will be discussed in more item in a afterwards unit of measurement of The Physics Classroom.) Always be cautious of the distinction between mass and weight. It is the source of much confusion for many students of physics.

Flickr Physics Photo

A i.0-kg mass is suspended from a leap calibration in an effort to determine its weight. The scale reads just brusk of 10.0 Northward - close plenty to call it 9.8 N. Mass refers to how much stuff is present in the object. Weight refers to the force with which gravity pulls upon the object.

Mass Vs Weight

Investigate!

Even on the surface of the Earth, there are local variations in the value of k that take very minor effects upon an object'due south weight. These variations are due to latitude, altitude and the local geological structure of the region. Utilize the Gravitational Fields widget below to investigate how location affects the value of thousand.

Sliding versus Static Friction

As mentioned above, the friction force is the force exerted past a surface as an object moves across it or makes an attempt to move across it. For the purpose of our study of physics at The Physics Classroom, there are two types of friction force - static friction and sliding friction. Sliding friction results when an object slides across a surface. As an case, consider pushing a box across a floor. The flooring surface offers resistance to the move of the box. Nosotros oft say that the floor exerts a friction force upon the box. This is an example of a sliding friction strength since it results from the sliding move of the box. If a machine slams on its brakes and skids to a terminate (without antilock brakes), there is a sliding friction forcefulness exerted upon the motorcar tires by the roadway surface. This friction force is also a sliding friction forcefulness because the car is sliding across the road surface. Sliding friction forces can be calculated from knowledge of the coefficient of friction and the normal force exerted upon the object past the surface it is sliding beyond. The formula is:

F_{frict-sliding} = μ_{frict-sliding} • F_norm

The symbolμ_{frict-sliding} represents the coefficient of sliding friction between the 2 surfaces. The coefficient value is dependent primarily upon the nature of the surfaces that are in contact with each other. For about surface combinations, the friction coefficients show niggling dependence upon other variables such as area of contact, temperature, etc. Values ofμ_sliding accept been experimentally determined for a multifariousness of surface combinations and are often tabulated in technical manuals and handbooks. The values of μ provide a measure of the relative amount of adhesion or allure of the two surfaces for each other. The more that surface molecules tend to attach to each other, the greater the coefficient values and the greater the friction force.

Friction forces can also exist when the two surfaces are not sliding across each other. Such friction forces are referred to every bit static friction. Static friction results when the surfaces of 2 objects are at rest relative to one another and a force exists on 1 of the objects to set it into motility relative to the other object. Suppose y'all were to push with 5-Newton of force on a large box to move it across the floor. The box might remain in identify. A static friction force exists between the surfaces of the floor and the box to prevent the box from existence fix into movement. The static friction force balances the force that you exert on the box such that the stationary box remains at residue. When exerting 5 Newton of applied strength on the box, the static friction force has a magnitude of 5 Newton. Suppose that you were to push with 25 Newton of force on the big box and the box were to still remain in place. Static friction at present has a magnitude of 25 Newton. Then suppose that you were to increase the force to 26 Newton and the box finally budged from its resting position and was ready into motion beyond the floor. The box-floor surfaces were able to provide upwardly to 25 Newton of static friction strength to match your applied strength. Yet the two surfaces were non able to provide 26 Newton of static friction force. The corporeality of static friction resulting from the adhesion of any ii surfaces has an upper limit. In this example, the static friction force spans the range from 0 Newton (if in that location is no force upon the box) to 25 Newton (if yous push on the box with 25 Newton of force). This human relationship is often expressed as follows:

F_frict-static ≤ μ_frict-static• F_norm

The symbol μ_frict-static represents the coefficient of static friction between the ii surfaces. Similar the coefficient of sliding friction, this coefficient is dependent upon the types of surfaces that are attempting to motion across each other. In general, values of static friction coefficients are greater than the values of sliding friction coefficients for the same two surfaces. Thus, information technology typically takes more force to budge an object into motion than it does to maintain the motion in one case it has been started.

The significant of each of these forces listed in the table in a higher place will have to exist thoroughly understood to be successful during this unit. Ultimately, you must be able to read a verbal description of a physical situation and know enough virtually these forces to recognize their presence (or absence) and to construct a free-body diagram that illustrates their relative magnitude and direction.

We Would Similar to Advise ...

Sometimes it isn't enough to just read about it. You have to interact with it! And that'southward exactly what you do when y'all use one of The Physics Classroom'southward Interactives. We would like to suggest that you combine the reading of this folio with the use of our Free-Torso Diagram Interactive. You can find it in the Physics Interactives section of our website. The Free-Torso Diagram Interactive allows a learner to practice identifying the forces that human action upon an object and to express such an understanding by the construction of a free-body diagram.