Lesson 3-4, An Introduction to Mechanical Technology Engineering Design Lesson 3-4, An Introduction to Mechanical Technology

Objectives Explain how mechanical systems enhance human capabilities Describe the factors that affect a mechanical system’s efficiency Analyze the functioning of the mechanical systems in the designed world Apply engineering design process to solve a problem

Mechanical Technology The assembly of mechanical components to produce, control, and transmit motion.

Common Components Levers Shafts Inclined planes Couplings Wedges Cables Wheels and axels Bearings Pulleys Brakes Screws clutches Gears Cams Linkages

Simple Controls Complex systems may have layers of controls Some controls operate particular parts of the system, while others control other controls Even the most fully automatic systems require human control at some point.

Performance Evaluations Mechanical Advantage To find the MA of a machine, you can divide the resistance force by the effort force. Most of the time the resistance force is the weight of the object in Newtons. Efficiency The resultant amount of work (output), divided by the amount of work put into the machine (input)

Scientific Concepts Force: a push or pull exerted by one object on another Motion: any physical movement or change in position or place Energy: the ability to do work. Work: the transfer of energy from one physical system to another, expressed as the product of a force and the distance through which it moves a body in the direction of the force Work (foot-pounds or Newton-meters) = Force (pounds or Newtons) x Distance (feet or meters)

Scientific Concepts (cont) Power: Force divided by time. Measured in foot-pounds, newton-meters, or watts. Gravity: the natural tendency of objects with mass to attract each other. Friction: a force that opposes the motion or intended motion of a body in contact with another body.