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PHYSICAL SCIENCES: PHYSICS (P1)

PREPARATORY EXAMINATIONS SEPTEMBER 2014

NATIONAL SENIOR CERTIFICATE

GRADE 12

Physical Sciences/P1/Grade 12 2 Limpopo DoE/September 2014 NSC


INSTRUCTIONS AND INFORMATION 1. Write your NAME in the appropriate space on the ANSWER BOOK. 2. This question paper consists of ELEVEN questions. Answer ALL the questions in

the ANSWER BOOK. 3. Start EACH question on a NEW page in the ANSWER BOOK. 4. Number the answers correctly according to the numbering system used in the

question paper. 5. Leave ONE line between two subquestions, for example between QUESTION 2.1

and QUESTION 2.2. 6. You may use a non-programmable calculator. 7. You may use appropriate mathematical instruments. 8. You are advised to use the attached DATA SHEETS. 9. Show ALL formulae and substitutions in ALL calculations. 10. Round off your FINAL numerical answers to a minimum of TWO decimal places. 11. Give brief motivations, discussions, et cetera where required. 12. Write neatly and legibly.



QUESTION 1: MULTIPLE-CHOICE QUESTIONS Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Write only the letter (A-D) of the answer next to the question number (1.1 – 1.10) in the ANSWER BOOK. 1.1 A trolley moves on a flat, horizontal surface when a constant force, F, is applied to

it.

Which ONE of the following physical quantities will ALWAYS remain constant while the trolley is moving?

A momentum

B acceleration C kinetic energy D gravitational potential energy

(2) 1.2 An object, moving vertically upwards, reaches a maximum height and falls back to

the ground. Ignore air resistance. Which ONE of the following statements is TRUE? The object experiences an acceleration which ….

A is always downwards B is first upwards and then downwards C is first downwards and then upwards D decreases first and then increases

(2) 1.3 A satellite experiences a gravitational force of magnitude F on the surface of the

earth. The radius of the earth is R. The satellite now circles the earth at an unknown height above the surface of the earth and experiences a gravitational force of magnitude ¼ F. This unknown height is ….

A R B 2 R C 3 R D 4 R

(2)

F



1.4 A spacecraft, made up of two modules R and J of masses 3m and m respectively,

is travelling horizontally at a velocity v due east. An explosion causes the two modules to separate.

Module J continues in its original direction immediately after the explosion with a velocity of 3v. What will be the magnitude and direction of module R’s velocity immediately after the explosion? Magnitude of velocity of R Direction of R after explosion A 1 v East B 1 v West C ⅓ v East D ⅓ v West (2)

1.5 A car moves from rest in a straight line under the influence of a constant net force.

Which ONE of the following graphs best represents the net work done (W) on the car in relation to its displacement (∆x)?

A B C D (2)

W

∆x

W

∆x

W

∆x

W

∆x

N

E

v

J m

R 3m



1.6 In which direction will an absorption spectrum shift during a red shift?

A towards the blue end of the spectrum. B to light of a shorter wavelength. C to light of a lower frequency. D. to light of a higher energy.

(2) 1.7 In the circuit shown below, bulbs X and Y are identical.

Which ONE of the following correctly describes the initial change in total resistance and the reading on the ammeter when switch S is closed?

R (Total Resistance) I (Ammeter Reading) A decreases unchanged B increases unchanged C increases decreases D decreases increases

(2)

X

S

A

Y



1.8 Two strong bar magnets are arranged with the North and South poles facing each

other as shown in the diagram below. A current – carrying conductor carries conventional current into the plane of the paper when placed between the poles of two magnets.

The conductor will experience a force towards ……

A A B B

C C D D

(2) 1.9 A small test charge +q is placed exactly half way between two identical negatively

charges, X and Y, each with a charge + Q, as shown below.

The test charge +q will A remain where it is B move towards X C move towards Y D move vertically downwards .

(2)

SOUTH NORTH

A

C

B D

+ Q +q + Q X d d Y



1.10 Monochromatic blue light is incident on a metal surface as shown in the circuit diagram drawn below. The intensity, I, of the incident blue light is gradually INCREASED.

Which ONE of the following graphs could represent the kinetic energy(EK), of the photoelectrons, ejected by the metal surface, as a function of the intensity (I)?

A B C D (2)

[20]

µA

Ek

I

Ek

I

Ek

I

Ek

I



QUESTION 2 (Start on a new page) The diagram below shows a 3 kg block connected to a 1 kg block by a light inextensible

string. A constant horizontal force of 20 N pulls the system along a rough horizontal

surface.

The frictional force between the blocks P and Q and the surface is 2 N and 1 N respectively. 2.1 State, in words, Newton’s Second Law of Motion. (2) 2.2 Draw a labelled force diagram showing ALL the horizontal forces acting on

the 3 kg block. (3)

2.3 2.3.1 Calculate the magnitude of the acceleration of the 3 kg block. (5)

2.3.2 Hence, determine the magnitude of the tension in the string. (2)

[12]

P Q

3 kg 20 N 1 kg

rough horizontal surface



QUESTION 3 (Start on a new page) The sketch below shows the motion of a ball that is thrown vertically upwards from a

balcony. It takes 0,4 s to reach its highest point, after which it falls downwards, past the

balcony, to the ground. Ignore the effects of friction.

3.1 From the graph, how high is the balcony above the ground? (1) 3.2 Without any calculation, what is the numerical value of time t1? (1) 3.3 Calculate the initial velocity of the ball. (3) 3.4 Calculate the maximum height, above the ground, reached by the ball. (4) 3.5 Calculate the magnitude of the final velocity of the ball when it reaches the ground. (3) 3.6 Draw a velocity versus time graph for the motion of the ball. Indicate the

following on your graph:

• initial velocity

• final velocity

• time taken to reach maximum height (3) [15]

t (s) t2 t1 0,4

8

Po

sit

ion

(∆

y)

m



QUESTION 4 (Start on a new page) A man pushes a crate, of mass 10 kg, up a rough surface inclined at 200 to the horizontal,

with a 100 N force parallel to the surface.

200 The crate is pushed 5 m up the surface with an initial speed of 1,5 m.s–1. The coefficient of

kinetic friction between the crate and surface is 0,4.

4.1 Draw a labelled free body diagram to show all the forces acting on the

crate. (4) 4.2 Calculate the work done by gravity. (3) 4.3 Calculate the:

4.3.1 energy lost due to friction. (6) 4.3.2 work done by the man in pushing the crate up the surface. (1) 4.4 State the Work Energy Theorem in words. (2) 4.5 Use the Work Energy Theorem to calculate the magnitude of the final velocity of the

crate after it has been pushed 5 m up the surface. (4) [20]



QUESTION 5 (Start on a new page) Two railway locomotives A, of mass 6000 kg and B, of mass 5000 kg, are moving on a straight horizontal track in the same direction at different constant speeds as shown in the sketch. The two locomotives collide, link together and move at 3 m.s–1 in the original direction immediately after the collision. 5.1 Is the collision between the two railway locomotives elastic or inelastic? Provide a reason for your answer. (2) 5.2 Calculate the initial velocity of the locomotive B before the collision. (6)

[8]

QUESTION 6 (Start on a new page) The siren of a stationary fire truck emits sound waves of frequency 1800 Hz. A car, travelling on a straight horizontal road at a constant speed of 30 m.s–1, passes the fire truck and continues at the same constant speed. 6.1 Name the medical instrument that makes use of the Doppler Effect. (1)

6.2 How does the pitch of the siren, heard by the driver of the car, change when the car is moving: (State only increase, decrease or remain the

same)

6.2.1 Towards the fire engine? (1)

6.2.2 Away from the fire engine? (1)

6.3 Calculate the frequency detected by the driver as the car moves towards

the fire truck. (Take the speed of sound in air as 330 m.s–1) (5) 6.4 Sketch a graph to show how the frequency of the siren changes as a function of time as the driver approaches and then passes the fire truck. (No numerical values are required) (3) [11]

vi = ? vi = 4 m.s–1

B A



QUESTION 7 (Start on a new page) Two identical metal spheres, A and B, on insulated stands are placed with their centres

10 cm apart as shown in the sketch below. Sphere A has a charge of –15 nC while sphere

B carries an unknown positive charge. P is a point 2 cm away from the centre of A, as

shown in the sketch.

The NET electric field at point P is 3,943 x 105 N.C–1 to the left. 7.1 Define the term electric field at a point. (2) 7.2 Draw the resultant electric field pattern due to the charges on A and B. (2) 7.3 Calculate the magnitude of the unknown charge on sphere B. (7) 7.4 Sphere B is removed. State whether the electric field at P, due to the charge on

sphere A, will INCREASE, DECREASE or REMAIN THE SAME. (1)

[12]

A B

P

8 cm 2 cm



12Ω

S r

10Ω

R

QUESTION 8 (Start on a new page) The battery in the circuit, represented in the diagram below, has an internal resistance r. When switch S is closed the reading on voltmeter V2 is 18 V and resistor R dissipates 13,5 W. 8.1 Calculate the resistance of resistor R. (3) 8.2 Calculate the reading on the ammeter. (5) 8.3 Explain, in words, what is meant by the term internal resistance. (2) 8.4 Calculate the potential difference across the 10 resistor. (3) 8.5 When switch S is opened the reading on voltmeter V1 changes to 45,9 V. Hence, calculate the internal resistance of the battery. (5)

8.6 Does the external resistance in the circuit INCREASE, DECREASE or REMAIN THE SAME when the resistor R is removed? (1)

[19]

A

V2

V1



QUESTION 9 (Start on a new page) A learner sets up the circuit shown below to investigate the relationship between potential difference and current for each of two unknown resistors X and Y. Ignore internal resistance. The learner obtained the following graphs from the investigation’s results. 9.1 State Ohm’s Law, in words. (2) 9.2 What does the gradient of the above graph represent? (1) 9.3 Without any calculation, state which resistor, X or Y, has the greater

resistance. Provide a reason for your answer. (2) 9.4 Use the graph to determine the resistance of resistor X. (4) [9]

12 V

A

X or Y

V

S

Cu

rren

t (A

)



QUESTION 10 (Start on a new page) Electric generators are described as either AC or DC generators. 10.1 What energy conversion takes place in all electric generators? (1) 10.2 Consider the simplified sketch of a generator below. The direction of the initially

induced current is indicated on the sketch.

10.2.1 Is the above generator an AC or a DC generator? (1) 10.2.2 Which specific part of the generator in the above sketch,

1, 2, 3, or 4 helps to identify the type of generator? (1) 10.2.3 In which direction (clockwise or anti-clockwise) is the coil between the magnets being rotated? (1) 10.2.4 Briefly explain why the induced emf is at a maximum when the coil is

parallel to the magnetic field. (2)

10.3 The graph of potential difference and time for the generator in question 10.2 is shown below.

If an rms current of 15 A is produced, determine the rate at which the generator will transfer energy. (5)

[11]

time (s)

Po

ten

tial

Dif

fere

nc

e (

V)

0

330

–330



QUESTION 11 (Start on a new page) A learner investigates the relationship between the kinetic energy of photoelectrons and

frequency when light is incident on a metal surface. The graph obtained by the learner was

found to cut the x – axis at f0 = 5 x 1014 Hz.

11.1 Is the metal, on which the light is incident, a cathode or an anode? (1) 11.2 What physical quantity does f0 represent? (1) 11.3 Define the term work function. (2) 11.4 Calculate the work function of the metal. (3)

11.5 Calculate frequency, f1, as shown on the graph. (5) 11.6 Does f0 INCREASE, DECREASE or REMAIN THE SAME when

different frequencies of light are used? (1)

[13] Grand Total: 150

Light

µA Sensitive Ammeter

vacuum Graph of kinetic energy versus frequency

f0

Ek (

x 1

0–19 J

)

f1

11

f (Hz)

Physical Sciences/P1 (Physics) Limpopo DoE/September 2014 NSC


17

Physical Sciences/P1 Limpopo DoE September2014 NSC


18

fK = µKN

fS = µSN


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