Module #1, Part 1- Fundamental Concepts and Definitions, Force & Force Systems Flashcards
is an applied science which describes and predicts the conditions of rest or motion of bodies under the action of forces.
is the foundation of most engineering sciences and is an indispensable prerequisite to their study.
Mechanics
- Rigid bodies
- Deformable bodies
- Fluids
Categories of Mechanics
- Statics
- Dynamics
Categories of Rigid bodies
needed to locate the position of a point in space. Distance is described in terms of a standard unit of ___
Length -
associated with the notion of the position of a point P given in terms of three coordinates measured from a reference point or origin
Space
definition of an event requires specification of the time and position at which it occurred
- Time -
used to characterize and compare bodies, e.g., response to earth’s gravitational attraction and resistance to changes in translational motion
Mass -
- represents the action of one body on another. A ___ is characterized by its point of application, magnitude, and direction, i.e., a force is a vector quantity.
- Force
- 1 ft = __in. (inches).
12
- ___ ft = 1 mi. (mile).
5280
___ lb = 1 kip (1 kilo-pound).
1000
- ___ lb = 1 ton
2000
N x 10^9
Giga
N x 10^6
mega
N x 10^3
kilo
N x 10^-3
milli
N x 10^-6
micro
N x 10^-9
nano
The weight of a body, or force of gravity exerted on that body, should also be expressed in ___.
Newton
Weight is a __
Force
Weight of a body Formula
W= mg
g=
9.81 m/s2 (32.2 ft/s2 )
on a body is a force generated outside the body (i.e. Load on the body)
External force
On a body is a force generated inside the body (to keep the body together
Internal force
__ is an external force on the body that tries to change the state of movement of the body.
ex. The force with which the earth attracts a person (the weight of the person)
Applied force
is an external force that inhibits change in the state of movement of a body when acted on by an applied force.
Reaction force
is a force density. (i.e. N/m
Distributed force
A sketch showing the physical conditions of the problem
Space Diagram:
: A sketch showing only the forces on the selected particle
Free-Body Diagram
forces are shown in a free-body diagram.
External
Force Systems According to Line of Action
forces whose lines of action pass through a common point
Concurrent forces
Force Systems According to Line of Action
forces whose lines of actions are parallel
Parallel forces
Force Systems According to Line of Action
Non-concurrent forces
- forces whose lines of actions are neither parallel nor intersect in a common point
the resultant force on a particle is zero, the particle will remain at rest or continue to move in a straight line
Newton’s First Law
A particle will have an acceleration proportional to a nonzero resultant applied force.
F= ma
- Newton’s Second Law
The forces of action and reaction between two particles have the same magnitude and line of action with opposite sense.
Newton’s Third Law:
external effect of a force on a body is the same for all points of application along its line of action.
Moving the point of application of the force F to the rear bumper does not affect the motion or the other forces acting on the truck.
Principle of Transmissibility
Problem Statement:
Free-Body Diagrams:
Fundamental Principles:
Solution Check:
Method of Problem Solution
Includes given data, specification of what is to be determined, and a figure showing all quantities involved.
Problem Statement
Create separate diagrams for each of the bodies involved with a clear indication of all forces acting on each body
Free-Body Diagrams
Determine what theories are required for solution. Write down the equations to be used. Make substitutions into the equations only after you are confident that all of the correct equations have been selected.
Fundamental Principles:
- Test for errors in reasoning by verifying that the units of the computed results are correct,
- test for errors in computation by substituting given data and computed results
- always apply experience and physical intuition to assess whether results seem “reasonable”
Solution Check:
