p60-73 Flashcards by d k

What are some examples of basic products that use mechanical systems

Secateurs or door closers

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What are basic products that use electronic systems

Kettles or toasters

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What is a mechanism

Series of parts that work to control forces and motion in desired way

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What is a force

Push pull or twist

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What are the 4 types of motion

Rotary
Linear
Oscillating
Reciprocating

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What is rotary motion

Circular seen in wheels
Counted in rpm

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Linear motion

Straight line
Vehicle or conveyor belt
Speed =d/t

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Oscillation

Back and forth in circular path
Eg swing/elec toothbrush
-measured in opm

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Reciprocating

Back and forth in a straight line
Eg jigsaw blade
Measured in opm

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What do mechanisms that control and change motion have

Input and output

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What is an example of a mechanisms input and output

Input is movement of handle
Output is movement of blades
In scissors

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What is the relation between force and distance in input and output mechanism

Inversely proportional

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What does a lever do

Controls and changes motion

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Parts of a lever

Bar that rotates on a fulcrum
Effort -input force
Load -output force

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Eg of a lever

Brake pedal
-foot of a driver applies load to brakes of car

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What is torque

Twisting force

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Torque and rotary speed relation

Inversely proportional

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What is a cam and follower

Mechanism that converts rotary to reciprocal

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What is a cam and follower

Cam-Special shaped wheel
Follower-rests on edge of cam

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Where and why are cams used

In machinery to produce desired motion

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3 types of cam

Snail
Pear shaped
Eccentric

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What is a spur gear

Wheel with teeth around edge

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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