Chapter 4 Centroid - Distr. Forces
Chapter 4 Centroid - Distr. Forces
Chapter 4 Centroid - Distr. Forces
Centroids &
Distributed forces
Introduction
In the previous chapters we treated
all forces as concentrated along their
lines of action and at their points of
application.
“concentrated” forces do not exist in
the exact sense, since every external
force applied mechanically to a body
is distributed over a finite contact
area, however small.
Introduction
Volume Distribution
Line Distribution Area Distribution
CENTERS OF MASS AND
CENTROIDS
Center of Mass
Determining the Center of
Gravity
Determining the Center of Gravity
Centroids of Lines, Areas,
and Volumes
Centroids of Lines
Centroids of Lines, Areas,
and Volumes
Centroids of Areas:
Centroids of Lines, Areas,
and Volumes
Centroids of Volumes
Sample Problem
Sample Problem
Sample Problem
Centroid of semicircular&
quarter-circular
Composite Bodies and
Figures; Approximations
Sample Problem
Sample Problem
Solution
Theorems of Pappus
A very simple method exists for calculating the surface area generated
by revolving a plane curve about a nonintersecting axis in the plane of
the curve
Theorems of Pappus
Theorems of Pappus
Ifa line or an area is revolved
through an angle θ less than 2π, we
can determine the generated
surface or volume by replacing 2π
by θ
Sample Problem
Determinethe volume V and surface area A of
the complete torus of circular cross section.
Sample Problem
Calculate the volume V of the solid generated by
revolving the 60-mm right triangular area through
180 about the z-axis. If this body were constructed
of steel, what would be its mass m?
Solution
Beams—External Effects
Determine
the reactions
at A and B for
the loaded
beam.
Problem 3
Determine the
reactions at A for
the cantilever
beam subjected to
the distributed and
concentrated
loads.
Problem 4
Findthe reaction at
A due to the
uniform loading
and the applied
couple.
Problem 5
Determine the
reactions at A and B
for the beam
subjected to a
combination of
distributed and point
loads.
Problem 6
Determine the force and moment reactions
at A for the beam which is subjected to
the load combination shown.