p60-73 Flashcards
What are some examples of basic products that use mechanical systems
Secateurs or door closers
What are basic products that use electronic systems
Kettles or toasters
What is a mechanism
Series of parts that work to control forces and motion in desired way
What is a force
Push pull or twist
What are the 4 types of motion
Rotary
Linear
Oscillating
Reciprocating
What is rotary motion
Circular seen in wheels
Counted in rpm
Linear motion
Straight line
Vehicle or conveyor belt
Speed =d/t
Oscillation
Back and forth in circular path
Eg swing/elec toothbrush
-measured in opm
Reciprocating
Back and forth in a straight line
Eg jigsaw blade
Measured in opm
What do mechanisms that control and change motion have
Input and output
What is an example of a mechanisms input and output
Input is movement of handle
Output is movement of blades
In scissors
What is the relation between force and distance in input and output mechanism
Inversely proportional
What does a lever do
Controls and changes motion
Parts of a lever
Bar that rotates on a fulcrum
Effort -input force
Load -output force
Eg of a lever
Brake pedal
-foot of a driver applies load to brakes of car
What is torque
Twisting force
Torque and rotary speed relation
Inversely proportional
What is a cam and follower
Mechanism that converts rotary to reciprocal
What is a cam and follower
Cam-Special shaped wheel
Follower-rests on edge of cam
Where and why are cams used
In machinery to produce desired motion
3 types of cam
Snail
Pear shaped
Eccentric
What is a spur gear
Wheel with teeth around edge
What is a pair of spur gears called
Spur train
What are gears in gear trains commonly
Diff size
What is a pinion
When input(driver gear )is smaller than the output (driver)
How is rotation carries to diff parts of a mechanism
By mounting a gear on a shaft(rod that transfers rotation through a mechanism)
What are the rules for diff size gears
Smaller gear is always faster
Rotate in opp directions
How is input rotational speed of gears reduced
Making driven gear larger than driver
What is a gearbox
Many simple gear trains working together to greatly reduce speed
What do gears systems need
Lubrication to lessen friction and prevent teeth wearing
Eg oil grease or graphite
What is another way other than spur gears transfer rotary motion
Pulley and belt
What makes pulley belts different from simple gear trains
Input shaft and output can be separated by greater distance in pulley
Input/output rotate in same direction
What is a linkage
Component that directs forces to where needed
What can linkages do
Convert between motion and change direction
Examples of linkages
Bell crank
Peg and slot
Crank and slider
Special shaped levers
What electronic systems does a car have
Control of engine
Navigation
What are electronic systems in buildings
Heating and ventilation and security systems
What are smaller parts of an electronic system
Subsystems which are inputs,processes and output
What do inputs consist of
Sensors that can measure physical quantities (light level temp or weight)
How are push buttons used in electronic systems
Push button senses it is pressed and a sensor displays an electrical signal which is sent into the subsystem
What are process subsystems commonly
Microcontroller
What are examples of outputs form process subsystems
Light sound or motion
Eg visual display screen on modern products
What is a programmable microcontroller
Components that follow program on how to perform tasks written by designer
What is embedding
Customising generic microcontrollers to specific application and permanently placing it within product
What makes microcontrollers attractive new technology
Small size
Versatility
Ease of use
What ar the capabilities of microcontrollers
Processing signals and performing calculations at high speeds
Add advanced features that enhance functionality of product and usefulness for user
What is an example of a microcontroller used in advanced tech
Smart fridge
What input /output do all microcontrollers use
Light sensor
Infrared sensor
Switch sensor
LEDs
Speakers and buzzers
Explain function of light sensor
Ldr connected to microcontroller
Signal produced when light level increases converted to number
Microcontroller makes decisions depending on how bright light is
Explain simple ir sensor
Produces signal when warm object is within range
Eg hand dryer or automatic tap
Explain passive ir sensors
Detect warm moving object
Eg used in burglar alarms/automatic lighting systems
What are the 3 types of switches
Tilt
Push to make
Time delay
Explain tilt switches
Produce signal when switch upright
Eg-used to sound alarm if object is tampered with
Explain time delay switch
Programmed by to stay on and off at various times at the day
Eg gaming consoles or tvs
What must be considered when using leds
Colour
Size
Shape
Brightness
Normal or flashing
