# Shared Flashcard Set

## Details

Statics Test 2
Review
79
Engineering
03/05/2013

Term
 Actual structures and machines, are always absolutely rigid and never deform under the loads to which they are subjected. T or F
Definition
 False Never absolutely rigid and deform
Term
 Forces acting on a rigid body can be represented by...
Definition
 sliding vectors
Term
 Two important concepts associated with the effect of a force on a rigid body are...
Definition
 the moment of a force about a point and an axis
Term
 The combination of two forces which have the same magnitude, parallel lines of action, and opposite sense...
Definition
 a couple
Term
 Any system of forces acting on a rigid body can be replaced by an equivalent system consisting of one force acting at a given point and one couple called a....
Definition
 force-couple system
Term
 In the case of concurrent, coplanar, or parallel forces, the equivalent FCS can be reduced to a single force called the ... of the system or to a single couple called the ....
Definition
 resultant resultant couple
Term
 Forces acting on rigid bodies can be separated into two groups:
Definition
 external and internal forces
Term
 The ________ represent the action of other bodies on the rigid body under consideration. They will either cause it to move or ensure that it remains at rest.
Definition
 external forces
Term
 The _________ are the forces which hold together the particles forming the rigid body. Forces holding the component parts together.
Definition
 internal forces
Term
 Two forces are said to be ________ (have the same effect on a rigid body) if they have the same magnitude, direction and same LOA.
Definition
 equivalent
Term
 The principle of transmissibility should be avoided or used with care, in determining....
Definition
 internal forces and deformations
Term
 The _______ property does not apply to vector products.
Definition
 commutative
Term
 The _________ property holds with vector products.
Definition
 distributative
Term
 The magnitude of MO measures the tendency of the force F to make the rigid body rotate about a fixed axis directed along MO. T or F
Definition
 True
Term
 Although the moment MO of a force about a point depends upon the magnitude, the LOA, and the sense of the force, it _____ depend upon the actual position of the POA of the force along its LOA.
Definition
 does not
Term
 The moment MO of a force F of given magnitude and direction ____________ of F.
Definition
 completely defines the line of action of
Term
 Two forces F and F' are equivalent if, and only if, they are equal (have same magnitude and direction) and have equal moments about a given point O. T or F
Definition
 True
Term
 The distributive property of vector products can be used to determine the moment of the resultant of several....
Definition
 concurrent forces
Term
 The moment about a given point O of the resultant of several concurrent forces is not equal to the sum of the moments of the various forces about the same point O T or F
Definition
 False is equal
Term
 The ________ of two vectors P and Q is defined as the product of the magnitudes of P and Q and of the cosine of the angle Θ formed by P and Q.
Definition
 scalar or dot product
Term
 The dot product of two vectors is....
Definition
 commutative and distributive P • Q = Q • P
Term
 The moment M of a couple is a ___________ which can be applied at any point.
Definition
 free vector
Term
 Two couples of F1 and -F1 and F2 and -F2 will have equal moments if...
Definition
 F1d1 = F2d2 , if the two couples lie in parallel planes (same plane) and have the same sense.
Term
 Two systems of forces are equivalent if we can transform one of them into the other by means of...
Definition
 1. Resultant of two forces on a particle 2. Resolving a force into two components 3. Canceling two equal and opposite forces acting on the same particle 4. Attaching to the same particle two equal and opposite forces 5. Moving a force along its line of action
Term
 The vector representing a couple is called a...
Definition
 couple vector
Term
 Any force F acting on a rigid body can be moved to an arbitrary point O provided that a couple is added whose moment is equal to the moment of F about O. T or F
Definition
 True
Term
 Any force-couple system consisting of a force F and a couple vector MO which are ___________ can be replaced by a single equivalent force.
Definition
 mutually perpendicular
Term
 Any system of forces, however complex, can thus be reduced to an ______________ acting at a given point O.
Definition
 equivalent force-couple system
Term
 The __________ of the system, is obtained by adding the moments about O of all the forces of the system.
Definition
 moment resultant
Term
 Two systems of forces are ________ if they can be reduced to the same force-couple system at a given point O.
Definition
 Equivalent
Term
 Two systems of forces, F1, F2, F3,....., and F'1, F'2, F'3,....., which act on the same rigid body are ________ if, and only if the sums of the moments about a given point O of the forces of the two systems are, respectively, equal.
Definition
 equivalent
Term
 To prove that two systems of forces are equivalent, the second of the relations must be established with respect to....
Definition
 only one point O (and will hold to any point if the two systems are equivalent.)
Term
 When two systems of vectors resultants and moment resultants about an arbitrary point O are respectively equal, the two systems are said to be...
Definition
 equipollent
Term
 If two systems of forces acting on a rigid body are equipollent, they are also equivalent. However this does not apply to _______ of vectors.
Definition
 any system
Term
 If two different system of forces acting on independent particles that do not form a rigid body are equipollent.   Since different forces will now act on the various particles, their effects on these particles will be different; the two systems of forces, while....
Definition
 equipollent, are not equivalent
Term
 The systems of forces which can be reduced to a single force, or resultant, are therefore the systems for which the force R and the couple vector MoR are mutually perpendicular if these three cases...
Definition
 1. Concurrent forces 2. Coplanar forces 3. Parallel forces
Term
 ....are applied at the same point and can therefore be added directly to obtain their resultant R. Always reduce to a single force.
Definition
 Concurrent forces
Term
 .... act in the same plane, which may be assumed to be the plane of the figure.
Definition
 Coplanar forces
Term
 ....have parallel lines of action and may or not have the same sense.
Definition
 Parallel forces
Term
 This particular force-couple system is called a _______ b/c the resulting combination of push and twist.
Definition
 wrench
Term
 A wrench consists of two _______ vectors, a force R and a couple vector. M1 = pR
Definition
 collinear
Term
 Whe the force and the couple are both equal to zero the external forces form a system equivalent to zero, and the rigid body is said to be in.....
Definition
 equilibrium
Term
 The necessary and sufficient conditions for the equilibrium of a rigid body can be obtained by setting ___ and ___ equal to zero.
Definition
 R and MOR
Term
 The conditions for equilibrium of a rigid body can be expressed in which six scalar equations...
Definition
 ΣFx = 0 ΣFy = 0 ΣFz = 0 ΣMx = 0 ΣMy = 0 ΣMz = 0
Term
 When the free body diagram is made of several parts, the forces the various parts exert on each other ________ be included among the external forces.
Definition
 should not
Term
 In solving a problem concerning the equilibrium  of a rigid body, all _________ should be indicated on the free-body diagram.
Definition
 external forces
Term
 The magnitudes and directions of the ___________ should be clearly marked on the free-body diagram.
Definition
 known external forces
Term
 Known external forces generally include the ______ of the free body and __________ for a given purpose.
Definition
 weight and forces applied
Term
 External forces represent the actions exerted ___ the free body ___ the ground and ___ the bodies which have been detached; they should be applied at the various points where the free body was supported by the ground or was connected to the other bodies.
Definition
 on by by
Term
 The _______ of the free body should also be included among the external forces, since it represents the attraction exerted by the earth on the various particles forming the free body.
Definition
 weight
Term
 _____________ usually consists of the reactions, through which the ground and other bodies oppose a possible motin of the free body.
Definition
 Unknown external forces
Term
 The reactions constrain the free body to remain in the same position, and, for that reason, are sometimes called...
Definition
 constraining forces
Term
 Reactions are exerted at the points where the free body is _________ or _________ other bodies and should be clearly indicated.
Definition
 supported by connected to
Term
 The reactions exerted on a 2-D structure can be divided into three groups corresponding to three types of supports or connections:
Definition
 Reactions Equivalent to a Force with Known line of Action, of Unknown Direction and Magnitude, and a Couple.
Term
 Supports and connections causing reactions of this type include rollers, rockers, frictionless surfaces, short link and cables, collars on frictionless rods, and frictionless pins in slots.
Definition
 Reactions Equivalent to a Force with Known Line of Action
Term
 Reactions Equivalent to a Force with Known Line of Action involve ___ unknown, namely, the....
Definition
 1 magnitude of the reaction
Term
 Supports and connections causing reactions of this type include frictionless pins in fitted holes, hinges, and rough surfaces.
Definition
 Reactions Equivalent to a Force of Unknown Direction and Magnitude
Term
 Can prevent translation of the free body in all directions, but cannot prevent the body from rotating about the connection.
Definition
 Reactions Equivalent to a Force of Unknown Direction and Magnitude
Term
 Reactions Equivalent to a Force of Unknown Direction and Magnitude involve two unknowns and are usually represented by their...
Definition
 x and y components
Term
 These reactions are caused by fixed supports, which oppose any motion of the free body and thus contrain it completely.
Definition
 Reactions Equivalent to a Force and a Couple
Term
 Reactions Equivalent to a Force and a Couple involve three unknowns, consisting usually of the two components of the _______ and the......
Definition
 force and the moment of the couple
Term
 While the three equations of equilibrium of a rigid body in 2-D cannot be .... by additional equations, any of them can be ... by another equation.
Definition
 augmented replaced
Term
 The types of supports that make it so the rigid body can not possibly move make the rigid body...
Definition
 completely constrained
Term
 While vertical motion is prevented the structure is  free to move horizontally. The structure is said to be....
Definition
 partially constrained
Term
 A rigid body is __________ whenever the supports, even though they may provide a sufficient number of reactions, are arranged in such a way that the reactions must be either concurrent or parallel.
Definition
 improperly constrained
Term
 Supports involving statically indeterminate reactions should be used with care in the _______ of structures and only with a full knowledge of the problems they may cause.
Definition
 design
Term
 The _______ of structures possessing statically indeterminate reactions often can be partially carried out by the methods of statics.
Definition
 analysis
Term
 Structures which are designed to move ________ be only partially constrained.
Definition
 should
Term
 A particular case of equilibrium which is of considerable interest is that of a rigid body subjected to two forces often called a...
Definition
 two-force body
Term
 It will be shown that if a two-force body is in equilibrium, the two forces must have the same _______, the same ______, and _______
Definition
 magnitude LOA opposite sense
Term
 A two-force body can be more generally defined as a rigid body subjected to forces acting at only....
Definition
 two points
Term
 a rigid body subjected to forces acting at only three points is called a...
Definition
 three-force body
Term
 Consider a rigid body subjected to s system of forces which can be reduced to three forces acting at three points. If the body is in equilibrium, the LOA of the three forces must be either ______ or _______
Definition
 concurrent or parallel
Term
 If a rigid body is in equilibrium, the sum of the moments of F1, F2 and F3 about any axis must be...
Definition
 zero
Term
 Express in vector form the conditions for the equilibrium of the rigid body considered.
Definition
 ΣF = 0     ΣMO = Σ(r × F) = 0
Term
 In problems involving the equilibrium of a 3-D structure, there can be between _________ unknowns associated with the reaction at each support or connection.
Definition
 1 and 6
Term
 With equilibrium of a 3-D body if the reactions involve more than six unknowns, some of the reactions are ________
Definition
 statically indeterminate
Term
 With equilibrium of a 3-D body if they involve fewer than six unknowns, the rigid body is only....
Definition
 partially constrained
Term
 With equilibrium of a 3-D body with six or more unknowns, the rigid body will be ___________ is the reactions associated with the given supports either are parallel or intersect the same line.
Definition
 improperly constrained
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