Chapter 6

Question 1

1: What is the difference between a system and a force?

2: Define Rotary Motion….

3: Define Linear Motion….

4: Define Oscillating Motion…..

5: Define Reciprocating Motion…..

Answer 1

1: Mechanism is an example of a system – these generate changes in motion – a force is the push, pull or twist and measured in Newtons.

2: Follows path of circle – found on wheels – measured in rpm / revolutions per minute

3: Motion in a straight line – found with vehicles. Measured by Speed=Distance/Time

4: Similar to circular motion – rotation moves back and forth in a circular path

5: Back & forth motion in straight line e.g. electric jigsaws

Question 2

1: Define what a CAM is. Give 3 different examples of CAM mechanisms.

2: Explain how a GEAR works.

3: How does a PULLEY AND BELT work?

4: What is the purpose of a linkage in a mechanism? What types of linkages are there?

Answer 2

1: A CAM and a follower is a mechanism to convert rotary motion into reciprocating motion. Snail CAM / Pear CAM / Eccentric CAM shown

2: A spur gear is a wheel with teeth – designed to link in with other gears of diff size – mounted as shafts (diff rotary speed)

3: Input & output shafts can be separated by a greater distance – shafts rotate in same direction

4: A component used to direct forces and movement to where they are needed – linkage changes motion or force. Research – BELL CRANK / PEG AND SLOT / CRANK AND SLIDER

Question 3

1: What must a mechanism have in order to control and change a motion?

2: A lever is an example of a mechanism that changes and controls motion. Explain how a lever works.

Answer 3

1: All mechanisms have an input and an output – research a pair of scissors for examples of movements and forces

2: The bar pivots on a fulcrum – input force of a lever is called the effort and the output force is called the load.

The distance between the fulcrum and the force is called the arm length.

Large arm length = large distance force must move = small force

Question 4

1: How would a system diagram be laid out showing the different subsystems in an electronic system?

2: Give examples of the following – Inputs / Outputs / Processes

Answer 4

1: See attached picture below

2: Inputs = Sensors – temperature / weight

Push Buttons – send an electronic signal

Processes = Made up of a programmable microcontroller

Outputs = Light / sound / motion / visual display.

Question 5

1: Name and describe the three most common OUTPUT devices

Answer 5

1:

Light Emitting Diode – Standard size of LED 5mm – LED range of colours, flashes

Speaker/Buzzer – microcontrollers are used with speakers to produce musical notes – not with buzzer

Motor –provides rotary motion when power recieved

Question 6

1: Name and describe the three main types of INPUT sensors in a circuit

Answer 6

1:

Light Sensor – Light Dependent Resistor (LDR) – detects when light is present – no light maybe a LED would come on

Infrared Sensor – IR sensors can detect movement – reflecting a beam back onto a sensor to trigger a light or a sound

Switch Sensor –Different types – tilt switch, push to make switch, time delay switch – others available