Newton's third law of motion ( Action and Reaction ! )

When a bullet is fired from a gun equal and opposite forces are exerted on the bullet and the gun during the time the bullet is passing down the barrel

Newton's second law of motion ( momentum , force , weight , free falling )

A motortruck requires a larger force to set in motion when it is heavily loaded than when it is empty

The nature of friction: Static and dynamic friction

Friction is the name given to the force which opposes the relative sliding motion of two surfaces in contact with one another. It plays a notable part in our daily lives. For example

Newton's Laws of motion:1- Newton's first law of motion

In 1687 Newton published a book written , as was the routine in those days , in Latin and given the title , Philosophiae naturalis principia mathematica Translated , this means

Derivation of Kinetic energy formula and worked examples

Where there are no opposing forces, a moving body needs noforce to keep it moving with a steady velocity ( Newton's first law of motion ). If, however, a resultant force does act on a moving body

Monday, July 22, 2013

technorati

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Saturday, March 23, 2013

The social impact of computers

The social impact of computers

Many businesses make use of electronic mail and electronic funds transfer to improve efficiency, reduce costs and speed up communication.

(a) State one advantage of using electronic mail instead of having a telephone conversation.

(b) Slate one difference between electronic mail and electronic funds transfer.

(c) Name two applications that might use electronic funds transfer.

(d) Describe how electronic mail and electronic funds transfer might change the work patterns and lifestyles of people using them.

Many goods and services can now be paid for using plastic cards. All the card companies use computers to work out the bills each month. This means t.hat the card company computers

store a lot of personal details about their customers and their purchases. If another organization got hold of the information it could be used against the card holder.

(a) Give two different organizations that might want to have access to this personal information.

(b) Explain why the card holder might suffer if these organizations did get access.

(a) Explain why the introduction of a computer system may result in unemployment.

(b) Explain why incorrect use of a computer system may result in a loss of privacy.

(c) Describe two methods which are used to ensure that data held on a computer is secure.

The argument that computers help increase unemployment is sometimes countered by saying that. the new microchip based technologies create job opportunities that. were unheard of 20 years ago.

(i) Describe how computers are replacing people in two distinct areas of employment.

(ii) Describe two broad areas of employment that did not exist before computers became available (excluding data processing).

(iii) Comment on the changes in employment patterns that have resulted from the development of computer technology.

Write down two computer applications which affect the work people do in an office.

The social impact of computers

Word processors may mean fewer typists

(a) Although some people may lose their jobs due to word processors, there are advantages to be gained by using them in an office.

Give two advantages gained by using word processors.

(b) As yet few workers have lost their jobs to computers. Name two kinds of jobs where people have had to retrain because of computers.

Use of Computers in industrial processes

Use of Computers in industrial processes

A greenhouse has a window which can be opened or closed under computer control. It also has a heater which can be switched on or off by the computer.

There is an electronic thermometer connected to the computer for measuring the temperature inside the greenhouse.

It is a very hot day so the window is open and the heater is off. At night there is a dramatic fall in temperature.

(a) How will the computer know about changes in temperature?

(b) List the two steps that the computer will take as the temperature falls.

A microprocessor system is used to control the heating in a house. The heating can be set to come on and off at particular times, and the temperature in each room can be individually set. Within each room there is a temperature sensor, and an electrically controlled valve to turn radiators on and off.

Use of Computers in industrial processes5

(a) Explain why the converters are needed.

(b) Discuss the advantages and disadvantages of using a computer controlled system compared with other control systems.

(a) Give two ways in which it is better to use robot welders rather than men.

(b) Give one way in which men are better than robot welders.

Many car manufacturers have introduced robots to their assembly lines.

(a) This involves a great deal of initial investment. Give two financial reasons why the companies might feel it worthwhile to introduce the robots.

(b) Robots must be taught to carry out their tasks. Explain how this is done.

(c) In paint shops, robots are used to spray paint the cars. Explain what can be done to make sure that the robots only spray paint when there is a vehicle there.

(d) The introduction of robots in car factories has increased the number of people required in some jobs and decreased the number in others.

(i) Name or describe two types of jobs in which the numbers have increased.

(ii) Name or describe two types of jobs in which the numbers have decreased.

(e) Describe a safety measure that may have been introduced as a direct result of having robots in the factory.

Technical , Scientific and Other Uses

Technical , Scientific and Other Uses

A runner is training for a 1500 m race. The coach is worried about the effects of running on the althete's heart and lungs. To monitor the runner there is a microcomputer system worn on a belt around her waist. There are sensors that will measure the following:

1 Breathing rate.

2 Heart rate.

3 Stepping rate.

These sensors are connected to the microprocessor. The microprocessor is connected to a radio transmitter. The transmitter sends the information collected to a track side computer system. This is shown in the diagram on the next page.

(a) What inputs are required for this data logging system.

(b) There is an output device connected to the belt microprocessor. This output device is not shown on the diagram. It gives urgent information to the runner.

(i) Describe or name a suitable device.

(ii) Give one use for this device.

Technical , Scientific and Other Uses

(c) The track side computer system also has an output device.

(i) Describe or name a suitable device.

(ii) Give one use for this device.

(d) Give one reason why there is a backing storage device provided on the track side computer.

(a) Mr and Mrs Glen wish to move to a new house. They are planning their dream home.

Technical , Scientific and Other Uses2 

Dream Homebuilders Ltd. build houses to customers' own specifications. They draw up plans and build models to give customers an idea of what their houses wilJ actually look like. If customers are not happy then plans are redrawn and new models built.

Mr and Mrs Glen contact Dream Homebuilders Ltd. Mrs Glen, who is a computer consultant, is surprised to find that the firm does not use computers in designing houses. She tells them about Computer Aided Design systems.

Describe two input and two output devices that the firm might need if they were to install such a system.

(b) I Describe how a Computer Aided Design system could be used to make changes to existing plans and produce new copies of them.

(c) Describe the advantages of the computerized system by comparing it with the manual system.

(d) Despite the cost of equipment and training, Dream Homebuilders Ltd decide to install a Computer Aided Design system. They also plan to keep on all of their existing employees. How can this be financially worth while?

Communications Systems and Word Processing

Communications Systems and Word Processing

(a) Name a teletext service that is available through an ordinary television signal.

(b) Name a widely used public View data service that uses the telephone network.

(c) Apart from costs and equipment, describe two main differences between these two forms of videotext.

(a) What is communications software?

(b) When would communications software be used'?

(c) Explain the difference between Ceefax/Oracle and Prestel.

(d) Explain why you often need a modem to transmit data between computers over a telephone link.

(e) Describe an application which would use communications software.

(a) View data systems such as Prestel provide users with a wide range of information. The diagram on p. 203 shows the stages necessary for a user to access a particular page of information. Complete the flowchart by choosing suitable statements from the list provided.

 

Statements

Enter page number

Enter password

Dial computer

Load communication software

Does the page exist ?

Exit code selected?

Copy page

Enter a key word

Communications Systems and Word Processing

(b) State the main charges that would be made for accessing information from Prestel. Your

answer should not include the cost of any equipment or software.

A class in Hilltown High School is using a word processing package to prepare a school recipe booklet.

(a) Tom has to key in a recipe for country scones. The recipe for country scones is very like the recipe for plain scones. Tom has already saved the recipe for plain scones as a file called 'plain'. Tom decides to enter the country scone recipe by loading the file 'plain' and editing it.

Here is part of the recipe for plain scones showing the changes to be made for country scones:

Communications Systems and Word Processing 2 

Fill in the blanks, using words from the following list, to describe the changes to be made:

Deleted inserted justified amended printed

line 1: 'Plain' has to be

line 3: '200' has to be .

and 'wholemeal' has to be

line 5: 'Pinch of Baking Powder' has to be .

(b) What program must be in t.he computer's memory before Tom edits the file 'plain'?

(c) Tom makes all the changes but doesn't save the new version under the name 'country'. He

saves it under the name 'plain' again.

Which scone recipe does 'plain' now contain?

(d) There is only one scone recipe on Tom's disc. Explain clearly what happened to the one that is 'lost'.

(e) Fortunately the teacher has a backup copy of the lost recipe on her disc.

Below are listed the steps that Tom has to follow to copy it back onto his disc .. Tom has only a single disc drive.

Step 1 is clearly marked. You have to mark steps 2, 3, 4 and 5.

Communications Systems and Word Processing 8

(f) At the end of each recipe there is a statement of its cost. For example, 'cost = £1.20'.

If the price of eggs or margarine goes up, the teacher has to work out the new cost of each recipe.

Here are different kinds of computer programs.

simulator graphics spreadsheet word processing

Which kind of program can do this calculation for you?

(a) The secretary at Freeman and Cumming uses a typewriter to type letters, legal documents and notes of meetings.

Some of the letters and legal documents are of the same basic form with individual client's details added. The final copy of legal documents must always be free from typing corrections. Some of these documents are very long.

Describe four facilities of a word processor that would be of particular help to the secretary to get through her work more quickly.

(b) Mr Freeman and Mrs Cumming are wondering whether to buy a word processor or employ an assistant secretary instead.

This is what Mr Freeman thinks:

I am against the idea of buying a word processor for these reasons.

1 We would need to spend a lot of money immediately on a word processor.

2 Word processors are less reliable than typewriters.

3 Our present secretary would have to go on a long and expensive training course.

4 An assistant secretary would, in the end, cost us more money but could do other office jobs like filing. A word processor could only be used to produce letters and documents.

I would therefore prefer to appoint an assistant secretary.

Mrs Cumming would prefer to buy a word processor. She intends to reply to Mr Freeman explaining why she agrees with some of these points but disagrees with others.

What should she say in reply?

(c) Mrs Cumming and Mr Freeman decided in the end to buy a word processor and they sent their secretary on a training course. She found the word processor very easy to use. Describe two features that could make word-processing packages user-friendly.

 

A school uses a word processor to produce a large number of standard letters. The letters are sent to parents informing them of the details of examination entries for their children. A data file containing details of each student's entries is merged with the document shown on the next page to produce the letters.

letter

Part of the document above will not be printed out when letters are sent to parents. Parts of the document will be replaced with items from the data file during the merge.

(a) Underline the part that will neither be printed nor replaced when letters are sent to parents.

(b) The data below represents part of the data file. It includes one full record and part of two other records.

Computer Studies

Mr Jones

Paul

Jones

Mathematics

French

English

Art

Mr& Mrs Hill

Sally

Explain how each field in the full record above would be included in the document to produce a letter that could be sent to a parent.

(c) Describe four ways in which a word processor might be used to improve the appearance and accuracy of such letters

Jops in computing

Jops in computing

Jops in computing

This is a list of jobs done by people working at the DVLC.

Job 1: Loading magnetic tapes.

Job 2: Altering the programs.

Job 3: Entering data into the computer.

Job 4: Managing the computer department.

Which of the above jobs is done by

(a) the computer operator?

(b) the keyboard operator?

Here is a list of job titles to do with computers:

Computer engineer

Data control clerk

File librarian Programmer

Shift leader

Computer operator

Data processing manager

Keyboard operator

Salesman

Systems analyst

For each of the tasks below, write down the most likely job title of the person doing it. You can use a job title once, more than once, or not at all.

(a) Loading a line printer with paper.

(b) Coding a computer program.

(c) Appointing new staff in a Data Processing Department.

(d) Correcting errors in a program.

(e) Finding the correct data tape.

(0 Testing a new computer system.

(g) Demonstrating a computer to a new customer.

(h) Keying in data.

(i) Repairing a faulty disc drive.

Briefly describe the work of

(a) A data processing manager.

(b) A computer operator.

(c) A data preparation operator.

A firm wants to install a computer. They have gone to a computer company for help. The systems analyst has investigated how the firm does its stock control manually. List or describe two further jobs he would do before the computer system is fully ready to replace the manual system.

Key-to-disc operators enter data into the computer system.

What other task is done by the key-to-disc operators?

What is the main task of a data preparation clerk working in a wages office?

Applications of Computers-commercial applications

Explain the following terms, giving an example in each case from a stock control system.

(a) File.

(b) Record.

(c) Field.

CASE STUDY

(a) What is contained in the re-order level field in the stock file?

(b) Describe fully when and how this field is used in conjunction with the re-order file.

Part of an employee's weekly payslip is shown below.

employee number employee name gross pay deductions net pay

023145 C. Newbury £400.00 £140.00 £260.00

To produce this payslip the employee number, employee name, deductions and rate of pay per hour are required. What one other piece of data is required?

Producing payslips for several thousand employees .

 

Producing details drawings for a computer aided design application

 

Producing high quality letters that can be sent to business customers

 

Producing listings for computer programs being developed on a microprocessor

 

(b) The payslip below was printed using preprinted stationery .

Jops in computing

Copy from the payslip above one item that would be preprinted on the stationery before the payslip was produced, one that was copied from the master file and one item that was calculated by the computer.

(c) State one reason for using preprinted stationery in this case.

A travel agent uses an on-line booking system to book seats on aircraft flights. The telephone system is used to communicate between the travel agency and the airline's computer.

(a) Give one advantage of having travel agencies connected on-line to the airline's computer in this way.

(b) Choose one of the following secondary storage devices which you consider to be most appropriate for the airline's computer. Give one reason for your choice.

a magnetic tape unit a floppy disc drive

a cassette tape machine a fixed disc store

(c) Whilst booking a seat for a customer there is a power failure at the travel agency. The power does not come back for an hour. Give one possible effect of this delay in communication.

Processing system

Processing system

Processing system

Which of these applications is an example of a real-time computer system?

A Controlling a nuclear reactor

B Printing wage slips

C Producing gas bills

D Searching a database

A computer system with a single disc drive and printer allows up to 50 users simultaneous access.

If two or more users attempt to print out reports at the same time, how would the system handle this?

Write down the names of the units marked A, Band C on the above diagram of a microcomputer.

These are all modes of computer operation.

For each of the applications given below write down the most suitable mode of operation.

(a) Controlling the signalling on an underground railway system.

(b) Updating the accounts in a Building Society overnight.

(c) A system to allow many students in a large Polytechnic access to the central database at the same time.

Tick the three applications in the list which would be carried out using batch processing.

Application

Uses batch processing tick (√)

Printing gas bills

Producing payslips

Airline bookings

Controlling a chemical plant

Producing invoices

Some schools and colleges have networks of computers.

(a) Give two advantages of a network of computers.

(b) Give one disadvantage of using a computer network.

Networks are used to ensure the efficient exchange of information.

(i) With the help of diagrams describe three different network configurations.

(ii) State two disadvantages of using the public telephone system for networking.

(iii) What is a multiplexor and how may it be used to advantage in a network?

Software

Software

Software2

Description: Programs and procedures, with their documentation, which can be implemented on a computer system.

Term:

Excluding games and entertainment software, most commercially produced software is either an application package or a utility program.

(a)

(i) Give one example of an application package.

(ii) Give one example of a utility program.

(b) Any good applications package has these features regardless of the task it is to do.

1 It must be robust..

2 In order to sell well it must be portable.

3 It must be reliable.

Explain what each of the underlined terms mean. You may use examples to help you explain.

CASE STUDY

Ring one item from the following list to complete the sentence.

an applications program a compiler

a utility program an algorithm

A program to sort the transaction file is called .

Which one of the following is a systems program?

A A stock control program

B A spreadsheet program

C A file-copying program

D A graphics package

E A program for a computerized personnel system

(a) An operating system is an essential feature of any general purpose computer system. This is true whether the computer system is a central mainframe with many users, some using remote terminals, or a personal computer with only one user.

Describe three of the jobs that need to be done by the operating system.

(b) Any computer system that holds personal, commercial, or military information needs protection from unauthorized access or use.

(i) For a central mainframe computer system there are many different ways in which it is possible to restrict access. Describe briefly three of the methods that might be used.

(ii) For a personal computer state two precautions not already given in your answer to part b(i).

files

files

CASE STUDY

Opposite each of the following statements ring whether it is true or false.

statement

Vehicle records are divided into fields

true

false

Vehicle fields are divided into files

true

false

Vehicle files are divided into records

true

false

Vehicle records are divided into files

true

false

Which of the following is suitable for storing in a fixed length field of 6 characters?

A Address

B Birthplace

C Date of birth D Name

A stock file is held on magnetic disc so that records can be read and updated in any order.

(a) What is the name of this type of access?

(b) Could the stock file reasonably be held on magnetic tape?

Explain your answer.

CASE STUDY

Two files used by the DVLC are the vehicle transaction file and the vehicle main file.

Write either transaction or main against each of these two descriptions.

(a) A file containing details of any changes to be made.

(b) A file holding a record of every vehicle registered in the U.K.

SEB Standard Specimen

(a) Peter has written a COMAL program for a project. He wants to make a back-up copy on another disc. His teacher gives him a disc. Explain why a new disc must first be formatted before it can be used to store programs.

files 2

(b) Peter has a computer system with one disc drive. He wants to make the back-up copy using the LOAD and SAVE commands. Write out a list of instructions for him to do this.

A master file and a sorted transaction file are stored on magnetic tapes. The transaction file has been checked and is known to contain only new records to be inserted into the master file. Describe how a new master file can be generated using the existing master file and the transaction file.

In the diagram below what is X?

A Grandfather file

B New master file

C New transaction file

D Unsorted transaction file

files

The contents of four files are shown below.

file A

file B

file C

File D

27

93

34

27

36

60

39

34

38

34

45

36

97

39

60

38

102

93

39

45

102

45

60

93

97

102

(a) State how utility routines could have been used to produce files C and D from files A and B.

(b) Describe the function of one other utility routine.

'Hacking' is where someone tries to gain illegal access to a computer system. This is usually done using a remote terminal or microcomputer.

(a) Give one example of harm that a 'hacker' might do if successful in breaking into a

computer system.

(b) One method of protecting computer systems from 'hackers' is to have a system of passwords or codes. These should be secret and known only to legal users. Some people use names of people close to them because they are easy to remember. Why is this not a good idea?

(c) Give a suitable password for a remote access computer system. Say why you have given it.

(d) Give one further simple method of protecting a computer system from 'hackers' trying to use remote terminals.

CASE STUDY

Several generations of vehicle master file are kept by the DVLC.

Why do they keep them when they are no longer up to date?

Which of these is used to guard against accidental loss of data?

A Keeping back-up copies of files

B Keeping files under lock and key

C Keeping terminals under lock and key

D Using passwords

In an application three generations of the master file are kept. What are these three generations normally called and why are they considered necessary? Why is it also necessary to keep generations of the transaction file?

Errors

Errors

Errors

The T40 microcomputer system has a high level language interpreter.

(a)

(i) Explain how a syntax error can occur.

(ii) Explain how you would find the syntax error.

(b)

(i) Give and explain an example of a logical error.

(ii) Explain how to find the logical error.

A program is executed and produces results which are found to be incorrect. List three

different methods the programmer can use to locate a mistake in the program.

A company records the workers clocking in and out times on time sheets. There is no night shift. The format for each sheet is: A five digit works number, followed by 5 or 6 pairs of times in 24 hour clock notation, (time of arrival followed by time of leaving), each field separated by a slash/. An example is shown below. It has three errors in it.

20023/0900/1703/170610859/0858/1659/090111702/08591170841090011330

(a) Find the three errors and draw a ring around each.

(b) For each error give a validation rule that might be used in the data entry program to detect it.

In a certain program, some checks are made when the user enters the year of birth. These are:

field length check range check character type check presence

parity check

(a) Write the correct term from the list above in the spaces provided.

Has something been entered?

Is it made up Of numbers only?

Is it before 1986 and after 1880?

Is the entry 4 digits long?

(b) The same program will also require the user to enter his place of birth. Write down three checks which may be made when this has been input.

(c) Complete the sentence:

Character type checks and range checks are both types of data

A date is to be entered into a computer program in the form ddmmyy where dd is the day of the month, mm is the month and yy is the year. For example 230481 would be the 23rd Apri11981. Describe clearly the three following validation techniques that could be used to test the data:

(a) Find the three errors and draw a ring around each.

(b) For each error give a validation rule that might be used in the data entry program to detect it.

In a certain program, some checks are made when the user enters the year of birth. These are:

field length check range check character type check presence

parity check

(a) Write the correct term from the list above in the spaces provided.

Has something been entered?

Is it made up Of numbers only?

Is it before 1986 and after 1880?

Is the entry 4 digits long?

(b) The same program will also require the user to enter his place of birth. Write down three checks which may be made when this has been input.

(c) Complete the sentence:

Character type checks and range checks are both types of data __

A date is to be entered into a computer program in the form ddmmyy where dd is the day of the month, mm is the month and yy is the year. For example 230481 would be the 23rd Apri11981. Describe clearly the three following validation techniques that could be used to test the data:

(a) Length check.

(b) Format check.

(c) Range check.

Part of a vehicle main me is shown below.

Field

Length

Description

Example

1

7

registration mark

D847TBH

2

7

vehicle make

BL

3

8

model

MAESTRO

4

6

colour

BLUE

5

4

engine size

1300

6

1

taxation class

P

Part of a vehicle main me is shown below.

(a) Why is the taxation class coded as a single letter?

(b) Whilst the data is being entered into the computer it is verified and validated.

(i) How would the data be verified?

(ii) Using the registration mark A123 XYZ describe the meaning of the term validation.

Integer overflow can happen whilst the CPU is executing an arithmetic instruction. Show how by working through a sum. Label the point where the integer overflow would occur. (Your sum may be in binary or in ordinary base 10 numbers).