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ENGR 34 Statics Chapter 1, Day 1 Intro
1
ENGR 34 STATICS
Vince Bertsch627 Analy Village
Pick up handouts and workbook from the front table a) Define mechanics & statics
b) Overview of the course logistics and resourcesc) Review units and vectorsd) Recap Newton’s Laws
Today’s Objectives
WHAT IS MECHANICS??•The study of what happens to a “thing”
when it gets “pushed”
WHAT IS STATICS??•The study of what happens to a “thing”
when it gets “pushed” but doesn’t accelerate
BRANCHES OF MECHANICS
Statics(no change in motion)
Dynamics(acceleration)
Rigid Bodies(don't change shape)
Deformable Bodies(do change shape)
Incompressible(hydrodynamics)
Compressible(aerodynamics)
Fluids
Mechanics(study of push on things)
Why do we care about statics? Why do we care about statics?
ENGR 34 Statics Chapter 1, Day 1 Intro
2
COURSE GOALS• Foundational knowledge of statics• Analytical problem solving skills• Calculator and computer skills• Working together• Free body diagrams• # of equations, # of unknowns
COURSE MATERIALS• Hibbeler, Engr. Mechanics Statics, 14th Ed
• Course workbook
• Mastering EngineeringMasteringEngineering.com
• My homepage profiles.santarosa.edu/vince-bertsch
• Course websitecanvas.santarosa.edu/courses/17349
Engr 34 Statics
Workbook
ESTIMATING UNIT CONVERSIONS
•1 m ≈ 3 ft•1 km ≈ 0.6 mi•25 mm ≈ 1 in
•1 kg ≈ 2 lb•10 N ≈ 1 kg
Just multiply or divide by 10 or 2.•1000N ≈ 1 vb
Estimating PracticeNo calculatorsFill in the table with estimated values in the other units.
pounds kilograms newtons
143
3241
22
ESTIMATING PRACTICE
VECTOR REVIEWVectors have both a magnitude and a direction.
Vector variable names: AB or F AB or F
Unit vectors: i, j, k, x, y, z, AB, F, i,j,k, e
Force values: F = 10#<100° (uses default defn for angle)F = 40 N 80° (uses picture to define angle)F = 10 lb T (uses default object tension defn)F = 15N (magnitude only, use arrow in diagram
for both direction and +/- significance)
^ ^ ^ ^ ^ ^ ^ ^ ^
2D COORDINATE CONVERSIONApproach #1 (manual):
Keep angles between 0 and 90,
sin for opposite, cos for adjacent,
do signs yourself.
Approach #2 (automatic):
Use standard defined angles,
(from x axis counter-clockwise),
input into calculator.
ENGR 34 Statics Chapter 1, Day 1 Intro
3
2D COORDINATE PRACTICE
2D Coordinate Conversions
30°X
Y
A5
A
Ay
x=
=
Write the trigonometric relationships, do not solve.
40°
=yB
xB =
Y
X9
B
C =
Y
7
or
or
50°
C
5cos(30°)
5sin(30°)
-9sin(40°)
-9cos(40°)
9cos(-130°)
9sin(-130°) 7/sin(40°)
NEWTON’S LAWS
I F=0 iff no change in motion
II F = ma
III Equal & Opposite
For Next Time:• Register for MasteringEngineering.com• Bring Calculator• Bring Workbook