Statics Exam 2- TH questions

Positive moments are ____, while negative moments are ______

CCW; CW

The sense (a.k.a. direction) of a force or couple moment having an unknown magnitude but known line of action can be __________. If the solution yields a negative scalar, this indicates that the sense is ______.

assumed; opposite

Given the vectors a=1i+3j+4k and b=2i+7j-5k , select the answer choice that yields: 43i-13j-1k

b x a

Zero-force members occur at ____ where only 2 members are connected and _____ do not act along either member

joints; external loads

For the scalar formulation, F is the _____ of one of the forces and d is the perpendicular distance or ______ between the forces

magnitude; moment arm

A particle has a _____, but a _____ that can be neglected

mass; size

Instead of "torque" we will use the term:

moment

Frames and machines are 2 types of structures which are often composed of pin-connected ______. _____ are used to support loads, whereas ______ contain moving parts and alter the effect of forces

multiforce members frames; machines

The MOJ is akin to _____ equilibrium. For each joint, there are _____ equations that can be solved. The MOS is akin to ______ equilibrium. For each joint, there are _____ equations that can be solved.

particle; 2 rigid body; 3

A rigid body has a number of ______ that remain at a ______ distance from one another

particles; fixed

For systems where the forces are concurrent, coplanar, or parallel, further simplification can occur because resultant force and resultant moment are:

perpendicular

Sort the steps for analysis of the MOJ

-Identification of zero force members -Draw a FBD of the entire truss -Draw the FBD of a joint with one or two unknowns -Apply the scalar equations of equilibrium -Determine all the required forces by repeating the previous 2 steps

Sort the steps for drawing a FBD of a frame or machine

-Isolate each part by drawing its outlined shape -show all the forces and/or couple moments that act on the part -Label or identify each known and unknown force and couple moment with reference to an established x-y coordinate system -Identify all the 2 force members in the structure and represent their FBD as having 2 equal but opposite collinear forces acting at their points of application

Match the constraint condition to the definition. -A body has more supports than EoE -A body has fewer forces that EoE -The reactive forces intersect as a common point or pass through a common axis or all the reactive forces are parallel

-Redundantly constrained -Partially constrained -Improperly constrained

According to the textbook, what are some examples of distributed loads

-The pressure of the wind on the face of a sign -The pressure of water within a tank -The weight of sand on the floor of a storage container

In 2D, particle equilibrium yields ______ equations and rigid body equilibrium yields _______ equations. In 3D, particle equilibrium yields ______ equations and rigid body equilibrium yields ______ equations.

2; 3; 3; 6

If a truss has 7 members, what is the number of joints necessary to be a simple truss?

5

Match the units of the loading intensity, w, with the system of units. FPS= SI=

=lb/ft =N/m

Which of the following is the most restrictive 2D support?

Fixed support

Which of the following is the most restrictive 3D support?

Fixed support

The joint connections are usually formed by bolting or welding the ends of the members to a piece of metal named as _____ that has a bunch of little spikes

Gusset/Truss Plate

The method of ___________ is used to determine internal loads

Method of sections

If the force tends to elongate the member, it is a ______ force. However, if it tends to shorten the member, it is a _____ force

Tension; Compression

Which operation gives the projection of the moment along an axis?

The dot product of the unit vector of the axis with the moment created by the force

Moving a force vector that is not along its line of action will create the same external effects on the body if a _______ is applied

couple moment or moment

The loads on the left and right sides of the section are __________ in magnitude, but ___________ in direction. Thus, taking the sum of both sides yields ________

equal; opposite; 0

When drawing a FBD of an entire body, which of the following is shown:

external forces and directions

Since a couple moment can act at any point, it is considered a ______ vector

free

Because moments have magnitude and direction they are ______

vectors