Statics Final LC

The line of action of the distributed load's equivalent force passes through the __ of the distributed load. a. Centroid b. Mid-point c. Left edge d. Right edge

A

The moment of a couple is called a __ vector. a. Free b. Spin c. Romantic d. Sliding

A

Consider three couples acting on a body. Equivalent systems will be __ at different points on the body. a. Different when located b. The same even when located c. Zero when located d. None of the above

B

If r = { 1 i + 2 j } m and F = { 10 i + 20 j + 30 k } N, then the moment of F about the y-axis is ___ N-m a. 10 b. -30 c. -40 d. None of the above.

B

The original force and couple system and an equivalent force-couple system have the same __ effect on a body. a. Internal b. External c. Internal and external d. Microscopic

B

The vector operation ( P x Q ) • R equals a. P•(QxR) b. R•(PxQ) c. (P•R)x(Q•R) d. (PxR)•(QxR)

B

Consider two couples acting on a body. The simplest possible equivalent system at any arbitrary point on the bod will have __. a. One force and one couple moment b. One force c. One couple moment d. Two couple moments

C

The resultant force (FR) due to a distributed load is equivalent to the __ under the distributed loading curve, w = w(x). a. Centroid b. Arc length c. Area d. Volume

C

When a particle is in equilibrium, the sum of forces acting on it equals __. A. a constant B. A positive number C. Zer D. A negative number E. An integer

C

A general system of forces and couple moments acting on a rigid body can be reduced to a ___. a. Single force 4 b. Single moment c. Single force and two moments d. Single force and a single moment

D

If a simple truss member carries a tensile force of T along its length, then the internal force in the member is ___. a. tensile with magnitude of T/2 b. compressive with magnitude of T/2 c. compressive with magnitude of T d. tensile with magnitude of T

D

If three couples act on a body, the overall result is that: a. The net force is not equal to 0 b. The net force and net moment are equal to 0 c. The net moment equal 0 but the net force is not necessarily equal to 0 d. The net force equals 0 nut the net couple moment is not necessarily equal to 0

D

In statics, a couple is define as __ separated by a perpendicular distance. a. Two forces in the same direction b. Two forces of equal magnitude c. Two forces of equal magnitude acting in same directions d. None of the above

D

One of the assumptions used when analyzing a simple truss is that the members are joined together by ___. a. welding b. bolting c. riveting d. smooth pins e. super glue

D

The beam and cable (with a frictionless pulley at D) support an 80 kg load at C. In a FBD of only the beam, there are how many unknowns? a. 2 forces and 1 couple moment b. 3 forces and 1 couple moment c. 3 forces d. 4 forces

Question 3 exam 2- answer c

If the directions of the force and the couple moments are reversed, then what will happen to the beam? a. The beam will lift from A b. The beam will lift at B c. The beam will be restrained d. The beam will break

Question 4 exam 2- answer a

. In the method of joints, typically ___ equations of equilibrium are applied at every joint. a. two b. three c. four d. six

a

A force of magnitude F, directed along a unit vector U, is given by F = a. F(U) b. U/F c. F/U d. F+U e. F-U

a

A position vector, rPQ is obtained by a. Coordinates of Q minus coordinates of P b. Coordinates of P minus coordinates of Q c. Coordinates of Q minus coordinates of the origin d. Coordinates of the origin minus coordinates of P

a

For the same magnitude of force to be carried, truss members in compression are generally made ___ as compared to members in tension. a. thicker b. thinner c. the same size

a

Forces common to any two contacting members act with ___ on the other member a. equal magnitudes but opposite sense b. equal magnitudes and the same sense c. different magnitudes but opposite sense d. different magnitudes but the same sense

a

If a block is stationary, then the friction force acting on it is ___. a. ≤μsN b. =μsN c. ≥μsN d. =μkkN

a

If { 5 j } m and F = { 10 k } N, then r x F equals {__} N-m a.50i b.50j c.-50i d.-50j e. 0

a

Moment of force F about point O is define as MO = __. a. rxF b. Fxr c. r•F d. r*F

a

Select the SI units for the moment of inertia for an area: a. m4 b. m2 c. kg•m2 d. kg•m3

a

Select the SI units for the product of inertia for an area: a. m4 b. m2 c. kg•m2 d. kg•m3

a

Simply supported beams are beams with ___ supports. a. Pin and Roller b. Roller and Fixity c. Fixity and Pin d. All of the above

a

The definition of the Product of Inertia for an area involves an integral of the form: a. ∫xydA b. ∫x2dA c. ∫xydm d. ∫mdA

a

The dot product can be used to find all of the following except __. a. Sum of two vectors b. Angle between two vectors c. Component of a vector parallel to another line d. Component of a vector perpendicular to another line

a

The dot product of two vectors P and Q is define as a. PQcosθ b. PQsinθ c. PQtanθ d. PQsecθ

a

The dot product of two vectors results in a __ quantity. a. Scalar b. V ector c. Complex d. Zero

a

The figures show a frame and its FBDs. If an additional couple moment is applied at C, then how will you change the FBD of member BC at B? a. No change, still just one force (FAB) at B. b. Will have two forces, BX and BY at B. c. Will have two forces and a moment at B. d. Will add one moment at B.

a

The triple scalar product u • ( r x F ) results in: a. A scalar quantity b. A vector quantity c. Zero d. A unit vector e. An imaginary number

a

. A column is loaded with a horizontal 100 N force. At which section is the internal load the lowest? a. P b. Q c. R d. S

b

. The moment of inertia of a composite area equal the ___ of the MoI of all of its parts. a. vector sum b. algebraic sum c. addition d. product

b

For a frictionless pulley and cable, tensions in the cable (T1 and T2) are related as __. a. T1>T2 b. T1=T2 c. T1 d. T1=T2sinθ

b

If a support prevents translation of a body, then the support exerts a ___ on the body. a. couple moment b. force c. Bothaandb d. None of the above

b

Internal forces are not shown on a free body diagram because the internal forces are __. (Choose the most appropriate answer) a. equal to zero b. equal and opposite and they do not affect the calculations c. negligibly small d. not important

b

P and Q are two points in a 3D space. How are the position vectors rPQ and rQP related? a. rPQ = rQP b. rPQ = -rQP c. rPQ = 1/rQP d. rPQ=2rQP

b

The definition of the Moment of Inertia for an area involves an integral of the form: a. ∫xdA b. ∫x2dA c. ∫x2dm d. ∫mdA

b

The formula definition of the mass moment of inertia about an axis is: a. ∫rdm b. ∫r2dm c. ∫mdr d. ∫m2dr

b

To study problems concerned with the motion of matter under the influences of forces, i.e., dynamics, it is necessary to locate a point called ___. a. center of gravity b. center of mass c. centroid d. None of the above

b

Two points in 3D space have coordinates P (1, 2, 3) and Q (4, 5, 6) meters. The position vector rQP is given by: a. {3i+3j+3k}m b. {-3i -3j -3k} m c. {5i +7j +9k} m d. {4i+5j+6k}m

b

. In the method of sections, generally a cut passes through no more than ___ members in which the forces are unknown. a. 1 b. 2 c. 3 d. 4

c

1. What is not true about a unit vector, UA? a. It is dimensionless. b. Its magnitude is one. c. It always points in the direction of positive x-axis. d. It always points in the direction of vector A.

c

A composite body in this section refers to a body made of ___. a. carbon fibers and an epoxy matrix b. steel and concrete c. a collection of "simple" shaped parts or holes d. a collection of "complex" shaped parts or holes

c

A friction force always acts ___ to the contact surface. a. normal b. at 450 c. parallel d. at the angle of static friction

c

Find the dot product of the two vectors P and Q. P = {5i + 2j + 3k} m Q = {-2i + 5j +4k} m a. -12m b. 12m c. 12m^2 d. -12 m^2 e. 10m^2

c

For the same case, consider the MoI about each of the four axes. About which axis will the MoI be the smallest number? a. Axis 1 b. Axis 2 c. Axis 3 d. Axis 4 e. Cannot tell

c

Force vector, F, directed along a line PQ is given by a. (F/F)rPQ b. rPQ / rPQ c. F (rPQ / rPQ) d. F (rPQ / rPQ)

c

Frames and machines are different as compared to trusses since they have ___. a. only two-force members b. only multi-force members c. at least one multi-force member d. at least one two-force member

c

If a dot product of two non-zero vectors is 0, then two vectors must be __ to each other. a. Parallel (pointing in the same direction) b. Parallel (pointing in the opposite direction) c. Perpendicular d. Cannot be determined

c

If a vertical rectangular strip is chosen, then what are the values of x and y? a. (x,y) b. (x/2 , y/2) c. (x,0) d. (x , y/2)

c

The ___ is the point defining the geometric center of an object a. center of gravity b. center of mass c. centroid d. None of the above

c

The composite method for determining the location of the center of gravity of a composite body requires ___. a. integration b. differentiation c. simple arithmetic d. All of the above

c

The parallel-axis theorem can be applied to determine ___. Note: MoI is the moment of inertia of an area and MMI is the mass moment of inertia of a body a. only the MoI b. only the MMI c. Both the MoI and MMI d. None of the above

c

The three scalar equations ΣFx = ΣFy = ΣMo = 0, are ___ equations of equilibrium in two dimensions. a. incorrect b. the only correct c. the most commonly used d. not sufficient

c

When determining the force in member HG in the previous question, which one equation of equilibrium is best to use? a. ΣMH=0 b. ΣMG=0 c. ΣMB=0 d. ΣMC=0

c

For the previous problem, imagine that you have drawn a FBD of member BC. What will be the easiest way to write an equation involving unknowns at B? a. ΣMC=0 b. ΣMB=0 c. ΣMA=0 d. ΣFY=0

d

If F={10i+10j+10k}N and G = {20 i + 20 j + 20 k} N, then F + G = {_} N? a. 10i+10j+10k b. 30i+20j+30k c. -10i-10j-10k d. 30i+30j+30k

d

If a dot product of two non-zero vectors equals -1, then the vectors must be __ to each other. a. Parallel (pointing in the same direction) b. Parallel (pointing in the opposite direction) c. Perpendicular d. Cannot be determined

d

In a multi-force member, the member is generally subjected to an internal ___. a. normal force b. shear force c. bending moment d. All of the above

d

In mechanics, the moment M acting on a section of a beam is called the ___. a. axial force b. shear force c. normal force d. bending moment

d

Internal forces are ___ shown on the free body diagram of the whole body. a. always b. often c. rarely d. never

d

When determining the moment of a force about a specified axis, the axis must be along ___________. a. The X-axis b. The Y-axis c. The Z-axis d. Any line in 3D space

d