325:(about 9.81 m/s on Earth). The normal force here represents the force applied by the table against the object that prevents it from sinking through the table and requires that the table be sturdy enough to deliver this normal force without breaking. However, it is easy to assume that the normal force and weight are action-reaction force pairs (a common mistake). In this case, the normal force and weight need to be equal in magnitude to explain why there is no upward acceleration of the object. For example, a ball that bounces upwards accelerates upwards because the normal force acting on the ball is larger in magnitude than the weight of the ball.
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person feel heavier). In an elevator that is accelerating downward, the normal force is less than the person's ground weight and so a passenger's perceived weight decreases. If a passenger were to stand on a weighing scale, such as a conventional bathroom scale, while riding the elevator, the scale will be reading the normal force it delivers to the passenger's feet, and will be different than the person's ground weight if the elevator cab is
36:
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caused by and perpendicular to the normal force acting on the passengers against the walls results in suspension of the passengers above the floor as the ride rotates. In such a scenario, the walls of the ride apply normal force to the passengers in the direction of the center, which is a result of
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In an elevator either stationary or moving at constant velocity, the normal force on the person's feet balances the person's weight. In an elevator that is accelerating upward, the normal force is greater than the person's ground weight and so the person's perceived weight increases (making the
328:
Where an object rests on an incline as in
Figures 1 and 2, the normal force is perpendicular to the plane the object rests on. Still, the normal force will be as large as necessary to prevent sinking through the surface, presuming the surface is sturdy enough. The strength of the force can be
225:
parallel to the ground. In another common situation, if an object hits a surface with some speed, and the surface can withstand the impact, the normal force provides for a rapid deceleration, which will depend on the flexibility of the surface and the object.
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On the more macroscopic level, such surfaces can be treated as a single object, and two bodies do not penetrate each other due to the stability of matter, which is again a consequence of Pauli exclusion principle, but also of the
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In the case of an object resting upon a flat table (unlike on an incline as in
Figures 1 and 2), the normal force on the object is equal but in opposite direction to the gravitational force applied on the object (or the
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221:. If the person stands on a slope and does not sink into the ground or slide downhill, the total ground reaction force can be divided into two components: a normal force perpendicular to the ground and a
916:
applied to the passengers as the ride rotates. As a result of the normal force experienced by the passengers, the static friction between the passengers and the walls of the ride counteracts the pull of
840:
between the atoms; the atoms themselves do not disintegrate because of the electromagnetic forces between the electrons and the nuclei; and the nuclei do not disintegrate due to the nuclear forces.
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at the surfaces of the objects. The atoms in the two surfaces cannot penetrate one another without a large investment of energy because there is no low energy state for which the electron
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When we define the center of the ride to be the positive direction, solving for the normal force on a passenger that is suspended above ground yields the following equation:
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up or down. The weighing scale measures normal force (which varies as the elevator cab accelerates), not gravitational force (which does not vary as the cab accelerates).
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The normal force is one of the several forces which act on the object. In the simple situations so far considered, the most important other forces acting on it are
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556:{\displaystyle \mathbf {N} =\mathbf {n} \,N=\mathbf {n} \,(\mathbf {T} \cdot \mathbf {n} )=\mathbf {n} \,(\mathbf {n} \cdot \mathbf {\tau } \cdot \mathbf {n} ).}
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With the normal force known, we can solve for the static coefficient of friction needed to maintain a net force of zero in the vertical direction:
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from the two surfaces overlap; thus no microscopic force is needed to prevent this penetration. However these interactions are often modeled as
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can be found by scaling the normal direction by the net surface interaction force. The surface interaction force, in turn, is equal to the
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Lieb, E. H. (1991). The stability of matter. In The
Stability of Matter: From Atoms to Stars (pp. 483-499). Springer, Berlin, Heidelberg
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unless there were a countervailing force from the resistance of the platform's molecules, a force which is named the "normal force".
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on the passengers, resulting in suspension above ground of the passengers throughout the duration of the ride.
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meaning "ordinary" or "expected". A person standing still on a platform is acted upon by
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that is perpendicular to the surface that an object contacts. In this instance
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Force exerted on an object by a body with which it is in contact, and vice versa
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and solving for the normal force on a passenger yields the following equation:
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685:{\displaystyle N_{i}=n_{i}N=n_{i}T_{j}n_{j}=n_{i}n_{k}\tau _{jk}n_{j}.}
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is the angle of the inclined surface measured from the horizontal.
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The parallel shear component of the contact force is known as the
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When we define upward to be the positive direction, constructing
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for an object on an inclined plane can be calculated as follows:
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is the distance of the passenger from the center of the ride.
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442:, is the projection of the net surface interaction force,
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describing the stress state of the surface. That is:
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260:) acting on a block. Weight is the product of mass (
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816:: it is a result of the interactions of the
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1228:A Course in Classical Physics 1 - Mechanics
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1203:. Vol. 1. Macmillan. p. 101.
1171:Pearson IIT Foundation Series: Physics
989:is the normal force on the passenger,
773:{\displaystyle \mu _{s}=\tan(\theta )}
1197:; Franklin, William Suddards (1898).
1173:. India: Pearson. pp. 3.1–3.37.
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962:{\displaystyle N={\frac {mv^{2}}{r}}}
808:Normal force is directly a result of
373:{\displaystyle F_{n}=mg\cos(\theta )}
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1083:{\displaystyle \mu ={\frac {mg}{N}}}
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1195:Nichols, Edward Leamington
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810:Pauli exclusion principle
277:of the object), that is,
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306:{\displaystyle F_{n}=mg}
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793:{\displaystyle \theta }
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110:November 2015
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43:This article
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52:Please help
47:verification
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18:Normal Force
731:The static
456:dot product
1252:Categories
1156:References
136:Figure 1:
80:newspapers
1098:μ
1060:μ
905:gravitron
818:electrons
788:θ
765:θ
759:
744:μ
658:τ
540:⋅
536:τ
532:⋅
504:⋅
365:θ
359:
230:Equations
196:geometric
152:mechanics
1134:See also
424:friction
313:, where
1263:Statics
919:gravity
563:or, in
428:gravity
321:is the
208:gravity
94:scholar
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1090:where
969:where
814:per se
452:vector
380:where
275:weight
204:normal
191:normal
154:, the
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1258:Force
1140:Force
903:In a
101:JSTOR
87:books
1232:ISBN
1175:ISBN
912:the
73:news
756:tan
728:).
356:cos
150:In
56:by
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1209:^
567:,
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1240:.
1183:.
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413:g
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170:n
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141:N
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