Intro, Terminology, and Ch. 2 Flashcards
What is Statics?
the study of the equilibrium of bodies under action of forces
What is Dynamics?
the study of objects in motion
What are two other areas of mechanics besides Statics and Dynamics?
- Mechanics of Materials
- Fluid mechanics
What is Newton’s 1st Law?
If an object is in motion, it will remain in motion. If an object is at rest, it will remain at rest.
(i.e. When sum of forces acting on an object is zero, the object will remain at rest if initially at rest.)
What is Newton’s 2nd Law?
Sum of forces = mass x acceleration
What is Newton’s 3rd Law?
Forces exerted by two objects on each other are equal in magnitude and opposite in direction.
(i.e. for every action there is an equal and opposite reaction)
What are the two basic models used in Statics?
- Particle
- Rigid bodies
Particle
has mass but no size or shape
What is the acceleration due to gravity?
9.8m/s2
32.2ft/s2
(considered constant but not truly)
For this class, pounds (lb) refers to ___ where as slugs refers to ___.
force [=] lb (pound force)
mass [=] slugs
Mass is:
- scalar quantity
- Amount of material in a body
- measure of inertia (measure of resistance to change)
- same in any gravitational field (independent of location)
- [=] slugs, kg (1 slug = 14.59 kg)
Weight is:
- Vector quantity
- Effect of gravity on a body
- measure of Force (exerted on a body by a gravitational field)
- varies with strength of g (dependent on location)
- [=] lb, N (1 lb = 4.448 N)
What is a rigid body?
a model of a material body or system of particles in which the distence between any two particles remains the same (ie. no deformation)
What is a scalar? Give examples.
a physical quantity that has magnitude only (can be specified without mentioning direction)
(eg. time, temperature, volume, mass, distance, speed)
What is a vector? Give examples.
a mathematical quantity (directed line segment) completely specified by mentioning magnitude, direction, and which adds according to the Parallelogram Rule
(eg. Displacement, position, velocity, acceleration, momentum, or force)
What is the magnitude of a vector?
its length
What are the 3 types of vectors?
- Free
- Sliding
- Bound
What is a free vector?
Has definite magnitude and direction but NO specific location in space
(eg. moment vector of a couple)
What is a sliding vector?
can be moved along a given line collinear with the vector’s line of action
(eg. force acting on a rotating rigid body)
What is a bound vector?
has a specified point of application (aka. fixed vector)
eg. a force acting on a deformable body
What are two vector quantities dealt with extensively in Statics?
Force and momentum
What is a force?
- a quantity which tends to change the state of motion of a body
- the action of one body on another
- (felt as a push or pull)
A force is characterized by:
- point of application
- its magnitude
- its direction (defined by the line of action {infinite straight line along which the force acts} and the sense {direction} of the force)
What are some ways forces can be classified?
- Concentrated force (load)
- Distributed load
- External forces
- Internal forces
- Collinear forces
- Coplanar forces
- Concurrent forces
- General space force systems