ENGMECH Finals Flashcards
Physical science which deals with the effects of forces on objects. Oldest of the physical sciences.
Mechanics
Name the three parts of Mechanics and define them.
- Statics - deals with rigid bodies which are stationary or at constant velocity under action of forces. (Equilibrium of rigid bodies)
- Dynamics - deals with rigid bodies that are in motion.
- Mechanics of Deformable Bodies - deals with the internal effects of applied forces on non-rigid bodies.
What are the basic concepts of engineering mechanics?
- Space
- Time
- Mass
- Force
What is the difference between a rigid body and a non-rigid body?
A rigid body does not deform under the action of large forces meaning change in distance between any two points is negligible for the purpose at hand. A non-rigid body deforms under the action of large forces meaning any change would be considered.
Types of bodies investigated in engineering mechanics
Particles, rigid bodies, and non-rigid bodies.
A particle remains at rest or continues to move in a straight line with uniform velocity if there is no unbalanced force acting on it.
Newton’s First Law of Motion (Principle of Equilibrium)
The acceleration of a particle is proportional to the vector sum of forces acting on it, and is in the direction of this vector sum.
Newton’s Second Law of Motion (F=ma)
The forces of action and reaction between interacting bodies are equal in magnitude, opposite in direction, and collinear.
Newton’s Third Law of Motion (Law of Inertia)
What law is a consequence of Newton’s second law of motion such that no acceleration is present when the force is equal to 0 and the particle is either at rest or is moving with a uniform velocity?
Newton’s First Law of Motion (Principle of Equilibrium)
1 slug = _____ kg
14.59
1 kip = _____ lbs
1000
What is the gravitational acceleration in U.S. units?
32.2 ft/s^2
Differentiate scalar and vector quantities
Scalar quantities has magnitude while vector quantities has magnitude with direction.
An action of one body on another. It is a vector quantity.
Force
What is the difference between the external effect of forces and the internal effects of forces?
The external effect of forces is manifested in, or tendency to change, the state of motion of a body upon which the force acts. In other words, if there is no change in motion, the forces are said to be in equilibrium. The internal effect of forces produces stresses and strains within the body acted upon. These occurrences depend on the material properties of the body and is studied in regards to strength of materials, elasticity, and plasticity.
A force may be applied at any point on its given line of action without altering the resultant effects of the force external to the rigid body to which it acts. Thus, whenever we are interested in only the resultant external effects of a force, the force may be treated as a sliding vector.
Principle of transmissibility
Define contact force and a body force and give examples.
Contact force is produced by direct physical contact. Example is tension and compression forces as well as friction. Body force is generated by a body within a force field. Some examples include gravitational force and magnetic fields.
A set of 2 or more coplanar (2D) or spatial forces (3D) that may or may not be in equilibrium
Force Systems
Force systems can be _____ , _____ , or _____ .
Concurrent, parallel, or non-concurrent and non-parallel
A force system wherein two or more forces whose line of action intersect at a common point.
Concurrent force system
A force system wherein two or more forces whose line of action will never intersect.
Parallel force system
A force system wherein two or more forces are neither concurrent nor parallel.
Non-concurrent non-parallel force system
A force system wherein all forces share a common line of action.
Collinear force system
Vectorial parts of a force that act in certain directions in a plane or space which together produce the same effect as the force itself.
Components of a force
Force components could be either _____ or _____ .
Rectangular or oblique
When a body is in equilibrium, the resultant of all forces acting on it is _________.
0
Defined as a body or group of bodies which can be conceptually isolated from all other bodies. A system may be a single body or a combination of connected bodies. The bodies may be rigid or non-rigid.
Mechanical System
A diagrammatic representation of the isolated system treated as a single body.
FBD
Branch of engineering mechanics which deals with the study of forces and their effects on particles and rigid bodies in motion.
Dynamics of Rigid Bodies
Study of geometry in motion
Kinematics
Kinematics is used to relate __________________ without reference to the cause of motion.
Displacement, velocity, acceleration, and time
Study of the relations existing between the forces acting on a body, the mass of the body, and the motion of the body.
Kinetics
The motion of a particle can be ___________ and __________.
Constrained - Particle is confined to a specific path (ex. sliding a bead along a wire)
Unconstrained - No physical guide to particle’s motion.
Motion along a straight line
Rectilinear Motion (constrained motion)
Distance is a ________ quantity while displacement is a ________ quantity.
Scalar, Vector
The resulting curvilinear motion is then obtained by a vector combination of the x and y components of the position vector, the velocity, and the acceleration.
Rectangular Coordinates
Type of kinetics that is concerned with concurrent force systems. It deals with translational forces.
Particle Kinetics
Type of kinetics that is concerned with non-concurrent forces. It deals with both translational and rotational forces.
Rigid Body Kinetics
The resultant of the external forces applied to a body composed of a system of particles is equivalent to the vector summation of the effective forces acting on all particles.
D’Alembert’s Principle
Resistance of the mass to a change in velocity
Inertia
Work resulting from virtual forces acting through a real displacement or real forces acting through virtual displacement
Virtual Work
Branch of Engineering Mechanics which deals with the study of the external and internal effects of forces and environmental factors on deformable bodies.
Mechanics of Deformable Bodies
The condition under which stress is constant or uniform throughout the surface of a body
Simple Stress or Uniform Stress
A load that is directed along the longitudinal axis of the member.
Axial Force
Axial forces that tend to elongate a member
Tension Force
Axial forces that tend to shorten a member
Compression Force
The intensity of an internal force, but acts on a surface that is parallel to the internal force.
Shear Stress
If two bodies are pressed against each other, compressive forces are developed on the area of contact. The pressure caused by these surface loads is called _______ .
Bearing Stress
A geometric quantity that measures the deformation of a body
Strain
Change in the body’s shape and size whenever a force is applied to the body. May also occur when the temperature of the body is changed.
Deformation
Type of strain which characterizes dimensional changes
Normal Strain
Type of strain which describes distortion (changes in angles)
Shear Strain
The main output from the tensile test is the _____ .
Stress-Strain Graph
Differentiate Deformation and Deflection
Deformation = Change in length
Deflection = Change in position
___________ is the highest stress on the stress-strain curve.
Ultimate Stress or Ultimate Strength
The point where the stress-strain diagram becomes almost horizontal.
Yield Point
