physical sciences p1 learner guide july 2011

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Physical SciencesPaper 1Winter School 20114 July 15 JulyLearners Guide


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Physical Sciences Paper 1 Exam Revision Learners GuideWinter School July 2011

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Introduction:

Have you heard about Mindset? Mindset Network, a South African non-profitorganisation, was founded in 2002. We develop and distribute quality andcontextually relevant educational resources for use in the schooling, health and

vocational sectors. We distribute our materials through various technology platformslike TV broadcasts, the Internet (www.mindset.co.za/learn) and on DVDs. Thematerials are made available in video, print and in computer-based multimediaformats.

At Mindset we are committed to innovation. In the last two years, we successfully rana series of broadcast events leading up to and in support of the NSC examinations

Now we are proud to announce our 2011 edition of Matric Exam Revision, which willbegin with our Winter School in July. Weve expanded the broadcast to support youin seven subjects - Mathematics, Physical Sciences, Life Sciences, MathematicalLiteracy, English 1st Additional Language, Accounting and Geography.

During our Winter School, you will get Exam overviews, study tips on each of thetopics we cover, detailed solutions to selected questions from previous examinationpapers, short question and answer sessions so you can check you are on track andlive phone in programmes so you can work through more exam questions with anexperienced teacher.

Getting the most from Winter SchoolBefore you watch the broadcast of a topic, read through the questions for the topic

and try to answer them without looking up the solutions. If you get stuck and cantcomplete the answer dont panic. Make a note of any questions you have. Whenwatching the Topic session, compare the approach you took to what the teacherdoes. Dont just copy the answers down but take note of the method used.

Make sure you keep this booklet for after Winter School. You can re-do the examquestions you did not get totally correct and mark your own work by looking up thesolutions at the back of the booklet.

Remember that exam preparation also requires motivation and discipline, so try tostay positive, even when the work appears to be difficult. Every little bit of studying,

revision and exam practice will pay off. You may benefit from working with a friend ora small study group, as long as everyone is as committed as you are. Mindsetbelieves that the 2011 Winter School programme will help you achieve the resultsyou want.

If you find Winter School a useful way to revise and prepare for your exams,remember that we will be running Spring School from the 3rd to 7th October andExam School from 19th October to 22nd November as well.
http://www.mindset.co.za/learnhttp://www.mindset.co.za/learnhttp://www.mindset.co.za/learnhttp://www.mindset.co.za/learn


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Programme Outline

The Mindset Winter School is designed to focus on two subjects each day. For eachsubject you will find the following sessions:

Examination Overview

This is a 15 minute session that gives details of what you can expect in eachexamination paper. Practical guidelines are also given on how to prepare for theday of the exam.

Topics Tips

In this session you will be given a 15 minutes summary of the key ideas you needto know, common errors and study hints to help you prepare for your exams.

Topic Session

An expert teacher will work through specially selected questions from previousexam papers.

Interactive Q & A

After every topic you will get the chance to test yourself.

Live Phone-in

This is your chance to ask your own questions. So submit your question to theHelp Desk and we might call you back to help you live on TV. All questions yousubmit will be answered within 48 hours as normal.

Winter Broadcast School Schedule


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Topic 1: Mechanics

Question 1The roof of a tall building is 25 m above the ground. A rigid ball of mass 0,3 kg fallsfreely when dropped from the roof. It strikes the concrete floor on the ground with

velocity v1. It bounces to a maximum vertical height of 6 m. The ball was in contact

with the floor for 0,9s. Ignore the effects of friction.

1.1. Calculate the velocity v1

when the ball first hits the floor. (3)

1.2. Calculate the impulse of the ball as a result of the collision. (7)

1.3. Calculate the magnitude of the net force exerted on the ball. (3)

1.4. Using the ground as zero reference, draw a sketch graph of position(displacement) versus time for the motion of the ball from its original height

until it reaches its second maximum height. Indicate the relevant positionvalues on the y-axis. 1 (4)

1.5. The rigid ball is now replaced with a softer ball of the same mass and volumeas the rigid ball. It is then dropped from the same height onto the concretefloor. Will the ball reach the SAME, GREATER or LESSER height comparedto the previous ball? Use principles of physics to explain your answer. (2)

Question 2A man of mass 87 kg on roller skates, moving horizontally at constant speed in astraight line, sees a boy of mass 22 kg standing directly in his path. The man grabs

the boy and they both continue in a straight line at 2,4 ms

-1

.

2.1 Calculate the man's speed just before he grabs the boy. Ignore the effects offriction. (4)

2.2 Is the collision elastic? Use a calculation to support your answer. (6)

2.3 After grabbing the boy, they both continue at a velocity of 2,4 ms-1

along astraight line until they arrive at a loose gravel surface near the end of the path.They now move at constant acceleration in a straight line through the loosegravel for 2 m before coming to rest. Calculate the magnitude of the forceexerted by the gravel surface on the man and the boy. (5)


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Question 3New cars have a crumple zone to help minimise injuries during accidents. In additionseat belts, air bags and padded interiors can reduce the chance of death or seriousinjury.

3.1 Use principles in Physics to explain how air bags can reduce the chance ofdeath or injury. (3)

3.2 In a crash test, a car of mass 1,2 x 103 kg collides with a wall and reboundsas illustrated below. The initial and final velocities of the car are 12 ms-1 tothe left and 2 ms-1 to the right respectively. The collision lasts 0,1 s.

Calculate the:3.2.1 Impulse of the car during the accident (4)

3.2.2 Average force exerted on the car (3)

3.3. How will the magnitude of the force exerted on the car be affected if the timeinterval of the collision remains 0,1 s, but the car does not bounce off thewall? Write down only INCREASES, DECREASES or REMAINS THE SAME.Explain your answer. (2)


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Topic 2: Waves, Sound and Light

Question 1Dolphins use ultrasound to scan their environment.When a dolphin is 100 m from a rock, it emits ultrasound waves of frequency

250 kHz whilst swimming at 20 m.s-1 towards the rock. Assume that the speed ofsound in water is 1 500m.s-1.

1.1 Calculate the frequency of the sound waves detected by a detector on the rock.(4)

1.2 When the dolphin is 50 m from the rock, another ultrasound wave of 250 kHzis emitted. How will the frequency of the detected sound waves compare withthe answer calculated in QUESTION 7.1? Write down only HIGHER, LOWERor REMAINS THE SAME. Explain your answer. (2)

Question 2Light of a single frequency pass through a single slit. The first minimum is observedat point P on a screen, as shown in the diagram below. Point O is the midpoint of the

central bright band. The distance OP is 2,5 cm and the slit width is 3,2 x 10-5

m.

2.1 What can be deduced about thenature of light from this observation? (1)

2.2 Explain how the minimum is formed atpoint P. (2)

2.3 If the wavelength of the incident light is 600 nm, calculate the distance Qbetween the screen and the slit. (5)

2.4 The original slit is now replaced by a second slit of different width, while thedistance Q and the wavelength of the incident light remain the same. DistanceOP changes to 4 cm.

2.4.1 How does the slit width of the second slit compare to that of the firstslit? Only write down GREATER THAN, SMALLER THAN or EQUALTO. (1)

2.4.2 Explain your answer to QUESTION 9.4.1 without performing acalculation. (2)


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Question 3The diagram below shows a metal plate that emits electrons when a certainfrequency of electromagnetic radiation is incident on it. The plate is connected to asource of potential difference and an ammeter as shown in the circuit below.

3.1 Name the phenomenon described above. (1)

When radiation of wavelength 555 nm is incident on the metal plate, electrons arereleased with zero kinetic energy.

3.2 Define the term work functionof a metal. (2)

3.3 Calculate the work function of this metal. (6)

3.4 How will the reading on the ammeter change if the intensity of theelectromagnetic radiation is increased? Write down only INCREASES,DECREASES or REMAINS THE SAME. Give a reason for your answer. (3)

3.5 Incident radiation with a longer wavelength is now used. How will the readingon the ammeter change? Write down only INCREASES, DECREASES orREMAINS THE SAME. (1)


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Topic 3: Electricity and Electromagnetism

Question 1The ability of capacitors to store charge makes them essential components inelectrical appliances. Users are often warned of the dangers associated with

capacitors inside appliances.

1.1 Briefly explain why it can be dangerous to touch a charged capacitor. (2)

1.2 A certain parallel plate capacitor consists of two identical aluminium plates,

each of area 2 x 10-4

m2

. The plates are separated by a distance of 0,03 mm, with airoccupying the space between the plates.

1.2.1 Calculate the capacitance of the capacitor. (4)

1.2.2 Calculate the charge stored on the plates of the capacitor whenconnected to a 6 V battery. (3)

1.3 How will the capacitance of the capacitor in QUESTION 10.2 change(INCREASES, DECREASES or REMAINS THE SAME) if:

1.3.1 Paper is used to fill the gap between the plates instead of air (1)

1.3.2 The distance between the plates is increased. (1)

Question 2The circuit diagram below shows a battery, with an internal resistance r, connectedto three resistors, M, N, and Y. The resistance of N is 2 and the reading onvoltmeter V is 14 V. The reading on ammeter A

1is 2 A and the reading on ammeter

A2 is 1 A.(The resistance of the ammeters and the connecting wires may be ignored.)

2.1 State Ohm's law in words. (2)

2.2 How does the resistance of M compare with that of N? Explain how youarrived at the answer. (2)

2.3 If the emf of the battery is 17 V, calculate the internal resistance of the battery.(5)


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2.4 Calculate the potential difference across resistor N. (3)

2.5 Calculate the resistance of Y. (4)

Question 3

A source provides an rms potential difference of 36 V to a 4 and an 8 speakerconnected in series, as shown in the diagram below.

3.1 Calculate the following:3.1.1 rms current through the 4 speaker (3)

3.1.2 Peak current through each speaker (3)

3.1.3 Average power dissipated by the 4 speaker (3)

3.2 Without using a calculation, state how the average power dissipated by the4 speaker compares with the power dissipated by the 8 speaker. Give areason for the answer. (3)

Question 4Electric motors are used in pumps, fans and compressors. Electric motors can beeither AC or DC. The diagram below illustrates one of these types of electric motors.

4.1 What type of electric motor (AC or DC) is illustrated in the diagram?Give a reason for your answer. (2)

4.2 If the loop turns in a clockwise direction, in what direction is the current insection AB of the loop flowing in the above diagram? Write down from A to B,or from B to A only. (1)

The motor in the diagram is now changed to operate as a generator.

4.3 On what principle does a generator operate? (1)

4.4 Draw a sketch graph of the potential difference versus time for this generator

while it is functioning. (2)


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Topic 1: Mechanics Solutions

Question 11.1

1.2

1.3

1.4

1.5 Smaller Contact time for softer ball is longer than for rigid ball According to

Fnet

t = p, the force exerted by floor on softer ball is smaller than on the rigid ball.


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Solutions Topic 2: Waves, Sound and Light

Question 11.1

Remains the same. The detected frequency is independent of the distance betweenthe source and observer.

Question 2

2.1 Wave nature

2.2 Wavefronts from the slit arrive at point P out of phase and interferedestructively.

2.3

2.4.1 Smaller than

2.4.2


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Question 3

3.1 Photoelectric effect

3.2 The minimum energy of light needed to emit (photo)electrons from a metal

3.3

3.4 Increases. With light of higher intensity more photons strikes the metalsurface per second

3.5 Decreases


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Solutions Topic 3: Electricity and Electromagnetism

Question 1

1.1 Discharges very fast when touched and can cause electric shock (that can

be fatal)

1.2.1

1.2.2

1.3.1 Increases

1.3.2 Decreases

Question 2

2.1 The current through a conductor is directly proportional to the potentialdifference across its ends at constant temperature.

2.2 Equal 2 A divides equally at T (and since IM = 1 A it follows that IN = 1 A)

2.3

2.4 VN = IRN = (1)(2) = 2 V

2.5 VY = 14 2 = 12 V VY = IRY 12 = (2)RY RY= 6


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Question 3

3.1.1

3.1.2

3.1.3

3.2

4.1 DC. A split ring-commutator and is used to ensure that the current in theloop remains in the same direction through the complete cycle.

4.2 B to A

4.3 Electromagnetic induction

4.4

physical sciences p1 learner guide july 2011

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