Engineering Essential Unit 2 Vocab

Ergonomic

A systems approach for analyzing the physical interaction of the human worker with his/her work environment to maximize productivity, quality, usability, safety, health, and comfort.

Work

(symbol W) is the energy transferred when a force F is applied to an object moving through a distance d.

Resistance force

Impeding effect exerted by one material object on another.

Simple machines

A mechanism that changes the direction or magnitude of a force.

Magnitude

The greatness of size or amount.

Compound machine

A machine made up of two or more simple machines.

Mechanical advantage

The ratio of the force produced by a machine to the force applied to it, used in assessing the performance of a machine.

Mathematical model

A representation of a real world situation or system using mathematical concepts and language.

First class lever

A lever where the FULCRUM is located between the LOAD and the EFFORT (EFL) → (ex. tongs)

Second class lever

A lever where the LOAD is located between the FULCRUM and the EFFORT (ELF) → (ex. Wheelbarrow)

Third class lever

A lever where the EFFORT is located between the FULCRUM and the LOAD (FEL) → (ex. shovel)

Fixed pulley

A first class lever that has an axle attached to a supporting structure and changes the direction of force.

Moveable pulley

A pulley with an axle in a movable block that is supported by two parts of the same rope. In a movable pulley, force directions stay constant.

Block and tackle pulley

Fixed and movable pulleys in combination that provide mechanical advantage and a change of direction for effort force.

Biomechanics

The science of movement (or mechanics) of a living body, including how muscles, bones, tendons, and ligaments work together to produce movement.

Fulcrum

The point on which a lever rests or is supported and on which it pivots.

Goniometer

An instrument for the precise measurement of angles

Population

All the values in a data set that are collected during an observation or experiment.

Mean

an average of a set of numeric data values. It is calculated by taking the sum of individual values divided by the number of individuals.

Median

A measure of center in a set of numerical data. The median of a list of values is the value appearing at the center of a sorted version of the list, or the mean of the two central values if the list contains an even number of values.

Mode

The value that occurs most frequently in a given data set.

Outliers

an extreme value that differs greatly from other values in a set of data. As a "rule of thumb", an extreme value is considered to be an outlier if it is at least 1.5 interquartile ranges below the first quartile (Q1), or at least 1.5 interquartile ranges above the third quartile (Q3).

Interquartile range

A measure of variability equal to Q3 minus Q1, the interquartile range represents the middle fifty percent of data values in an ordered data set.

Measurable

Able to be measured. Measurable design criteria should provide a precise indicator of a quantifiable characteristic so that a design can be compared to the criteria and deemed acceptable or unacceptable

Abstraction

Abstract; (noun) The result of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics; (verb) The process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics.

Prototype

A working model used to test a design concept by making observations and necessary adjustments.

Computer aided design (CAD)

A process that uses a computer to assist in designing something, such as a part, circuit, or building.

Solid modeling

The process of creating a solid model or three dimensional object using a modeling and design application on a computer.

Additive method

A solid modeling design method where an object is created by adding volume to a smaller object.

Subtractive method

A solid modeling design method where an object is created by subtracting volume from a larger object.

Geometric primitives

The simplest two dimensional or three dimensional geometric shape.

Rapid prototyping

A process for quickly constructing a scale model of a physical part or system using three dimensional computer aided design models.

Additive manufacturing

A rapid prototyping method where three dimensional objects are built by adding layer upon layer of material.

Filament

A slender threadlike object, strand, or fiber used in additive manufacturing and threedimensional printing.

Extruder

A metal piece or die that is heated and forces plastic filament or metal through a shaped hole to produce a continuous ribbon of the material.

Linkage

An assembly of links connected at joints used to transfer an input motion to a desired output motion usually in a two dimensional plane.

Pins

A cylindrical machine component used as a fastener to constrain the relative movement between connected parts; In many cases, but not all, a pin is used to constrain connected parts to rotation about the axis of the pin.

Curvilinear motion

A combination of linear motion in two directions resulting in curved lines of motion.

Torque

A twisting force that tends to cause rotation.

Gear train

A mechanism used for transmitting rotary motion and torque through interlocking teeth.

Driver gear

Input gear or effort

Idler gear

a gear wheel that is inserted between two or more other gear wheels

Driven gear

Output gear or load

Gear ratio

A mathematical model that represents the behavior of the gear train.

Proof of concept

Experimental evidence that demonstrates that a design concept is feasible.

Project charter

A document issued by the project initiator or sponsor that formally authorizes the existence of a pro­ject and provides the project manager with the authority to apply organizational resources to project activities.