Mechanical Devices and Electronical Systems Flashcards
Define
mechanism.
a series of parts that work together to control forces and motion
Define
system.
the general name for a set of mechanical or electronic parts that work together to produce a desired ouput
Define
force.
and give its units.
a push, a pull or a twist
measured in newtons (N)
What is
rotary motion?
and what is it measured in?
motion that follows the path of a circle
e.g. rotation of wheels
it is commonly measured in revolutions per minute (rpm)
What is the equation for
speed?
speed = distance/time
What is
oscillating motion?
and what is it measured in?
similar to circular motion, but the rotation moves back and forth in a circular path
e.g. an electric toothbrush head
it is measured in oscillation per second (or per minute)
What is
reciprocating motion?
and what is it measured in?
back-and-forth motion in a straight line
it is measured in oscillations per second (or per minute)
Define
input.
(in terms of motion)
the type of motion put into a mechanism
Define
output.
(in terms of motion)
the type of motion a mechanism produces
Define
lever.
a rigid bar that turns around a fulcrum
Define
fulcrum.
the pivot around which a lever turns
Define
effort.
the input force
Define
load.
the output force
Define
arm length.
the distance between the force being exerted and the fulcrum
Define
torque.
a turning or twisting force
What can
rotary mechanical systems do?
(2 things)
- reduce rotary speed but increase torque
- increase rotary speed but reduce torque
Define
cam and follower.
a mechanism to convert rotary motion into reciprocating motion
How does a
cam and follower work?
A cam is a specially shaped wheel
The follower rests on the edge of the cam.
As the cam rotates, the follower moves up and down.
Define
spur gear.
a wheel with teeth around its edge
Define
simple gear train.
a pair of gears consisting of a driver gear and a driven gear
Define
pinion.
a small driver gear
(smaller than the driven gear)
Define
shaft.
a rod that transfers the rotation through a mechanism
What are the
two key rules for gears of different sizes?
- the smaller gear will rotate faster than the larger gear
- the gears will rotate in opposite directions
Define
lubrication.
a substance applied to reduce friction between moving parts
Define
pulley and belt drive.
a method of transferring rotary motion between two shafts
What are the two characteristics of
pulley and belt drives
that are different to simple gear trains?
- the input shaft and the output shaft can be separated by a greater distance in pulley and belt drives
- the input and output shafts rotate in the same direction in pulley and belt drives
Define
linkage.
a component used to direct forces and movement to where they are needed
Define
subsystem.
a section with a specific role within a system
Define
system diagram.
a diagram of the interconnections and flow of signals in an electronic system
Define
sensor.
a component that produces a signal in response to a specific physical quantity
Define
physical quantity.
something that can be measured
e.g. light, speed, temperature
Define
signal.
an electrical voltage that is used to represent information
Define
microcontroller.
a programmable electronic component that adds functionality to a product
Define
program.
a set of instructions to tell a microcontroller how to carry out a task
Define
embedding.
customising a microcontroller to be permanently placed within a product
What are some examples of
input sensors?
(3)
- light sensor
- infrared sensor
- switch sensor
How does a
LDR (light sensor) work?
it produces a signal that rises when the light level increases
What are the two different types of
infrared sensors?
and how do these work?
- simple IR sensor - produces a signal when it detects a warm object within range
- passive infrared sensor (PIR) - detects a moving warm object
What are
switch sensors?
very simple electronic components that can either be off or on
What are some different types of
switches available?
(4)
- latching push switch
- tilt switch
- momentary push switch
- time delay switch
Define
latching switch.
a switch that stays on (or off) after the button is released
Define
momentary switch.
a switch that stays on only while it is held pressed
What are some examples of
output devices?
(4)
- light emitting diodes (LEDs)
- speakers
- buzzers
- motors
What is a
motor?
a component that produces rotary motion when it receives power
