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Engineering Fundamentals: Statics and Dynamics

Engineering Fundamentals: Statics and Dynamics. TEC 303. Statics. Statics is concerned primarily with the equilibrium of bodies subjected to force systems. Forces and moments are the two entities that are of most interest in statics. Mathematically, forces are represented by vectors.

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Engineering Fundamentals: Statics and Dynamics

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  1. Engineering Fundamentals:Statics and Dynamics TEC 303

  2. Statics • Statics is concerned primarily with the equilibrium of bodies subjected to force systems. • Forces and moments are the two entities that are of most interest in statics. • Mathematically, forces are represented by vectors. • A moment may be thought of as a tendency to rotate the body upon which it acts about a certain axis.

  3. Moments No Moment TorqueorTwisting Moment

  4. Force • A force is a vector that represents pushing or pulling. Two or more forces that are applied to a part can be combined to determine the resulting effect of the forces.

  5. Torque • A moment or torque is the twisting action produced by force. A moment is a property that is stated relative to a reference point. • Moments are expressed in the units of force multiplied by distance (in-lb or ft-lb, Nm) • The moment of a force not only has magnitude but also a direction (clockwise or counterclockwise). • A moment is any twisting action of a force. • Torque is a specific amount of a moment.

  6. Mass and Weight • Mass is a measure of the amount of material in an object. • Weight of an object is a measure of the pull of gravity on it. • The center of gravity of an object is the balance point of that object. • The moment of inertia (the tendency of a body to resist acceleration) is dependent on the mass of the object along with the shape and size of the object.

  7. Scalars and Vectors • A scalar is a quantity (magnitude) • A car traveling 50 mph. • A vector has a quantity and a direction • A car traveling North 50 mph. Length = Magnitude

  8. Statics Example 1

  9. Statics Example 2 String Using string, drinking straw(s),tape, and a weight, construct anartifact that will hang from thewall and support the weight. Drinking Straw Weight Wall

  10. Statics Example Using string, drinking straw(s),tape, and a weight, construct anartifact that will hang from thewall and support the weight. String ∑ FY = 0 (Weight + F string sin0 = 0) Drinking Straw ∑ Fx = 0 (F string cos0 + F straw = 0) Weight Wall

  11. Equilibrium • For an object to remain static, the forces and moments on it must total to zero. • ∑ F = 0 • ∑ Fx = 0

  12. Dynamics • Dynamics is separated into kinematics and kinetics. • Kinematics is the study of motion (without forces). • Kinetics is the study of forces on bodies of motion.

  13. Kinematics • Kinematic analysis involves determination of position, displacement, rotation, speed, velocity, and acceleration. • This analysis provides insight into significant design questions

  14. Laws of Motion • Every object remains at rest, or moves with constant velocity, unless an unbalanced force acts upon it (static equilibrium). • A body that has an unbalanced force has • Acceleration proportional to the force (F =ma) • Acceleration in the direction of the force • Acceleration that is inversely proportional to the mass of the object (F = ma) • For every action, there is an equal and opposite reaction.

  15. Velocity • Linear velocity of a point is the linear displacement (vector) of that point per unit of time. Change in Position Change in Time = Velocity ∆P ∆T

  16. Velocity Continued • The magnitude of velocity is usually represented as speed. • A point can move in either a straight or curved path. • A box of doughnuts on a conveyor belt (linear) • Gears used to drive the dough needed for the doughnuts (curved)

  17. Acceleration • Linear acceleration of a point is the change of linear velocity of that point per unit of time. • Velocity is a vector • A change in either the magnitude or direction of velocity constitutes acceleration. Change in Velocity Change in Time = Acceleration ∆V ∆T

  18. Thermodynamics • Involves the storage, transformation, and transfer of energy. • energy cannot be created or destroyed; rather, the amount of energy lost in a process cannot be greater than the amount of energy gained. (1st Law) • energy systems have a tendency to increase their entropy (disorder/dilution) rather than decrease it. (2nd Law)

  19. Resources • Statics http://www.eng.iastate.edu/efmd/statics.htm • Active Statics http://acg.media.mit.edu/people/simong/statics/data/ • Dynamics http://www.engageengineering.org/?page=56 • Dynamics http://emweb.unl.edu/negahban/em373/intro.htm • Physics Classroom http://www.physicsclassroom.com/ • Thermodynamic Equilibrium http://jersey.uoregon.edu/vlab/Thermodynamics/ • Thermodynamic Experiments http://sci-toys.com/scitoys/scitoys/thermo/thermo.html

  20. Pictorial Examples of Statics

  21. Pictorial Examples of Dynamics

  22. Pictorial Examples of Thermodynamics

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