PHYSICAL SCIENCES: PHYSICS (P1) · Title: Microsoft Word - WKP KWOD PHYSC P1 Sept 2014 ENG Author:...

Physical Sciences/P1 1 CWED September 2014 NSC

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CAPE WINELANDS EDUCATION DISTRICT

PHYSICAL SCIENCES: PHYSICS (P1)

SEPTEMBER 2014

MARKS 150

TIME 3 hours

This question paper consists of 14 pages and 3 data sheets.


Copyright reserved Please turn over

INSTRUCTIONS AND INFORMATION 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12

Write your name in the appropriate space on the ANSWER BOOK. This question paper consists of TEN questions. Answer ALL the questions in the ANSWER BOOK. Start EACH question on a NEW page in the ANSWER BOOK. Number the answers correctly according to the numbering system used in this question paper. Leave ONE line between two sub questions, for example between QUESTION 2.1 and QUESTION 2.2. Write neatly and legibly. You may use a non-programmable calculator. You may use appropriate mathematical instruments. YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS. Show ALL formulae and substitutions in ALL calculations. Round off your FINAL numerical answers to a minimum of TWO decimal places. Give brief motivations, discussions, et cetera where required



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) next to the question number (1.1–1.10) in the ANSWER BOOK.

1.1 John, who is standing in a lift, observes a 20N mass piece suspended from

a spring balance fixed to the roof of the lift. He sees that the reading on the

spring balance is less than 20N for a short time interval. During this short time

interval the lift is …

A. not moving. B. accelerating upwards. C. accelerating downwards. D. moving with constant velocity. (2)

1.2 The gravitational force which the earth exerts on the moon is …..

A. directly proportional to the distance between their centres. B. inversely proportional to the mass of the moon.

C. inversely proportional to the product of the mass of the moon and the

mass of the earth. D. inversely proportional to the square of the distance between their centres. (2)

1.3 Two trolleys, X (mass m ) and Y (mass 2m) are stationary on a horizontal plane.

There is a compressed spring between the two trolleys as shown in the diagram below.

The spring is now released. How will the momentum of the trolleys compare? The momentum of trolley X ……

A. Will be greater than the momentum of trolley Y.

B. Will be less than the momentum of trolley Y.

C. Will have the same magnitude as the momentum of trolley Y.

D. Will be identical to the momentum of trolley Y. (2)



1.4 The graph below shows the position of a particle, with time, moving in a straight

line in a vertical plane.

Which ONE of the following velocity – time graphs best represents the motion of the particle?

(2)

1.5 A ball is thrown vertically upwards. Which ONE of the following physical quantities

of the ball will be zero when the ball reaches maximum height?

A. Acceleration

B. Kinetic energy

C. Gravitational potential energy

D. Weight (2)

1.6 A vehicle is travelling at a constant speed towards a stationary observer.

Its hooter produces sound waves of frequency 400 Hz. Ignore the effects of wind. The sound heard by the observer will most likely have a frequency, in hertz, of …

A. 400

B. 350

C. 380

D. 480 (2)



1.7 The centres of two identical metallic spheres, each carrying a charge Q, are a

distance r apart. Which ONE of the following pairs of changes (that are made simultaneously) will double the electrostatic force that one charged sphere exerts on the other?

(2) 1.8 When electrical energy must be transported over long distances, the energy loss

can be minimized if: A. the current is high and the voltage is low

B. the voltage is high and the current is low

C. both the current and voltage is low

D. both the current and voltage is high (2)

1.9 Which ONE of the following graphs best represents the relationship between

the electrical power and the current in a given ohmic conductor?

A

B

C

D

(2)

Distance between centres of spheres

Magnitude of charges

A decrease distance to 2

r double the charge on each sphere

B decrease distance to 2

r reduce the charge on one sphere to

2

Q

C decrease distance to 2

r reduce the charge on each sphere to

2

Q

D decrease distance to 2

r double the charge on each sphere

I

P

I

P

I

P

I

P



1.10. The two resistors in circuit 1 below are identical. They are connected in series to

a cell of emf V and negligible internal resistance. The power dissipated by each resistor is P.

The two resistors are now connected in parallel, as shown in circuit 2 below.

The power dissipated by each resistor in the circuit 2 is … A 2P

B 4P

C 8P

D 16P (2) [20]



QUESTION 2 [START ON A NEW PAGE] 2.1 Truck A, of mass 4 500 kg travels at a CONSTANT VELOCITY OF 50 km·h-1

while towing Bakkie B, of mass 1 250 kg. The engine of Truck A produces a force of 11 270 N. The road surface exerts a friction force of 8 820 N on Truck A.

2.1.1 Write down Newton’s Second Law of motion in words. (2) 2.1.2 Draw a free-body diagram showing ALL the forces acting on Truck A. The length of the vectors should be an indication of their relative magnitudes.(6) 2.1.3 Calculate the coefficient of kinetic friction for tyre rubber on the road surface. (3) 2.1.4 Calculate the force of friction exerted by the road surface on Bakkie B. (3) 2.1.5 Calculate the tension in the tow rope. (3)

2.2

Truck A suddenly stops. Unfortunately Bakkie B has no brakes and slams into the rear of Truck A and Bakkie B comes to an immediate stop. As a result of the collision, the tow rope breaks

2.2.1 Write down the Law of Conservation of Momentum in words.

(2)

2.2.2 Calculate the speed of Truck A immediately after the collision.

2.2.3 Using Newton’s First Law of motion explain why it is always advisable to tow with a solid bar instead of a tow rope.

(4) (2) [25]

Bakkie B Truck A



QUESTION 3 [BEGIN ON A NEW PAGE]

Sandile, who is standing on a platform, throws a small metal ball vertically upward, from a height of 1,73 m above the ground, into the air at 8 m·s-1. The ball travels pass the top of the building and returns to Sandile’s hand which is still at 1,73 m above the ground. Ignore the effects of friction.

Top floor window

2,5 m

building

8 m·s-1

1,73 m

ground platform

3.1 With what speed does the ball strike Sandile’s hand? (1)

3.2 Using an equation of motion and NOT energy principles, calculate the maximum

height that the ball reaches above the ground. (4)

3.3 If a window on the top floor of the building is at a height of 2,5 m above Sandile’s hand, calculate the time taken for the ball, from the moment it was thrown, to pass the top of the window on its return to Sandile’s hand. (5)

3.4 Taking upward direction as positive, draw a sketch graph of position versus time graph of the ball’s motion from the moment it left Sandile’s hand until it lands back into his hands. Indicate all relevant position values. Use Sandile’s hand as reference. (5)

[15]




A rescue helicopter is stationary (hovers) above the ground. It lowers a crate containing medical supplies with a mass 50 kg onto the ground below. When the crate is at a height of 20 m above the ground it has a speed of 2 m·s-1. The crate is lowered at a constant acceleration onto the ground with a cable, where it eventually comes to rest. Assume there is no sideways motion during the descent. Air friction is NOT to be ignored.

4.1 Define a non-conservative force. (2) 4.2 Identify TWO non-conservative forces acting on the crate during its downward

descent (motion). (2) 4.3 Draw a free-body diagram showing ALL the forces acting on the crate while it

is being lowered to the ground. (3) 4.4 Write down the work-energy theorem in words. (2) 4.5 Using the work energy theorem, calculate the acceleration of the crate as it is

lowered to the ground. (6)

[15]



QUESTION 5 [BEGIN ON A NEW PAGE] Use the diagram below to answer the following questions.

5.1 Identify the medical device shown in the diagram. (1)

5.2 Explain very briefly how the device functions and what it may be used for. (2)

5.3 A fire truck with its siren on, moves away at constant velocity from a person standing next to the road. The person measures a frequency which is 90% of the frequency of the sound emitted by the siren of the fire truck.

5.3.1 Name the phenomenon observed. (1)

5.3.2 If the speed of sound in air is 340 m·s-1, calculate the speed of the fire truck. (4)

[8]


Three +100 µC point charges, A, B and C, are equally spaced on a straight line in a

vacuum. The charges are a distance of 3 cm from each other as shown in the sketch below.

6.1 Define in words electric field at a point. (2) 6.2 Draw the electric field lines associated with charge A only. (2) 6.3 Calculate the magnitude of the electric field strength at the position where

charge B is and due to charge A only. (3) 6.4 Write down Coulomb’s Law in words. (2) 6.5 Calculate the net electrostatic force experienced by point charge C due to

charges A and B. (8)

[17]




Candice and Andisiwe conduct an investigation to determine the emf (ε) and the internal

resistance (r) of an unknown battery by experiment using three resistors. They use the

circuit below with first one resistor in series, then two resistors in series and then three

resistors in series. They also connect a voltmeter and an ammeter in this circuit.

When switch S was closed, they obtained the following results:

Number of resistors Voltmeter reading (V) Ammeter reading (A)

3 10,2 1,5

2 9,6 2,0

1 7,8 3,5

7.1 Sketch this circuit in your answer book. Show in your sketch where the learners

connected the ammeter and the voltmeter. (2)

7.2 Calculate the value of ε and r that they obtained in their investigation by using

their results. (7)

[9]




In the circuit represented below, the battery has an unknown internal resistance and an

emf of 12 V. When current flows through the circuit, the voltmeter across the battery reads

10 V and a voltmeter across R2 reads 4 V

8.1 Explain what is meant by the emf of a cell. (1)

8.2 Calculate the current through R1. (4)

8.3 Determine the internal resistance of the battery. (3)

8.4 Determine the resistance of R3. (4)

8.5 Explain what would happen to the current and resistance in the circuit if R3 was

removed from the circuit and replaced with a wire of negligible resistance.

Hence what will happen to the reading on V1. (4)

[16]




Electric motors are used in pumps, fans and compressors. Electric motors can be either

AC or DC. The diagram below illustrates one of these types of electric motors.

9.1 What type of electric motor (AC or DC) is illustrated in the diagram?

Give a reason for your answer. (2)

9.2 The diagrams A to D below show four positions in sequence during the

anti-clockwise rotation of the coil of a simple AC generator.

9.2.1 Name the fundamental principle on which generators work. (1)

9.2.2 What is the purpose of the slip rings in an AC generator? (1)

9.2.3 By referring to the relative positions of the coil in positions A to D,

draw the corresponding graph of potential difference versus time for

one full rotation (A to D to A). Indicate the positions of the coil (by

using the letters A to D) on your graph. (3)



C

9.3 A certain AC generator (alternator) produces a peak current (Imax) of 6,43 A when

connected to an electrical heater of resistance 48,4 Ω.

9.3.1 Calculate the rms current (Irms) produced by the generator. (3)

9.3.2 Calculate the peak voltage (Vmax) output of the generator. (5)

[15]


The apparatus below was used to explore the photo-electric effect using a

piece of zinc metal and light of a particular frequency. Use the diagram below to

answer the following questions.

10.1 Provide labels for B and C. (2)

10.2 Define the term” photo-electric effect” (2)

10.3 The learners observe that when component B is irradiated with light of

wavelength of 100 nm, a current is detected in the ammeter. The work function

of the metal B is 8,7 x 10-19 J. Calculate the speed at which

the electrons are emitted. (6)

[10]

GRAND TOTAL: 150



DATA FOR PHYSICAL SCIENCES GRADE 12 PAPER 1 (PHYSICS)

GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 12

VRAESTEL 1 (FISIKA) TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES

NAME/NAAM SYMBOL/SIMBOOL VALUE/WAARDE

Acceleration due to gravity Swaartekragversnelling

g 9,8 m·s-2

Gravitational constant Swaartekragkonstante

G 6,67 x 10-11 N⋅m2⋅kg-2

Radius of Earth Straal van Aarde

RE 6,38 x 106 m

Coulomb’s constant Coulomb se konstante

K 9,0 x 109 N⋅m2·C-2

Speed of light in a vacuum Spoed van lig in 'n vakuum

c 3,0 x 108 m·s-1

Charge on electron Lading op elektron

e -1,6 x 10-19 C

Electron mass Elektronmassa

me 9,11 x 10-31 kg

TABLE 2: FORMULAE/TABEL 2: FORMULES

MOTION/BEWEGING

tavv if ∆+= 2

21

i ta∆tv∆x ∆+= or/of 2

21

i ta∆tv∆y ∆+=

xa2vv2

i

2

f ∆+= or/of ya2vv2

i

2

f ∆+= ∆t2

vv∆x fi

+= or/of ∆t

2

vv∆y fi

+=

FORCE / KRAG

maFnet = p = mv

vmtFnet ∆=∆

if mvmvp −=∆ mgw =

2

21

r

mGmF=

2r

GMg =

N

fkk =µ

N

f)maks(s

s =µ



WORK ENERGY AND POWER / ARBEID, ENERGIE EN DRYWING

θ∆= cosxFW mghU = or/of mghEp =

2mv2

1K = or/of 2

k mv2

1E =

KWnet ∆= or/of knet EW ∆=

if KKK −=∆ or/of kikfk EEE −=∆

UKWnc ∆+∆= or/of pknc EEW ∆+∆= t

WP

∆=

aveave FvP =

WAVES, SOUND AND LIGHT/GOLWE, KLANK EN LIG

λ= fv f

1=T

s

s

LL f

vv

vvf

±

±= hfE = or/of

λ=

hfE

maxo KWE += or/of (max)ko EWE += where/waar

hfE = and/en 00 hfW = and/en 2maxmax mv

2

1K = or/of 2

max(max)k mv2

1E =

ELECTROSTATICS / ELEKTROSTATIKA

2

21

r

QkQF = (k = 9,0 x 109 N⋅m2·C-2)

2r

kQE = (k = 9,0 x 109 N⋅m2·C-2)

q

FE =

q

WV =

e

Qn = of/or

eq

Qn =

CURRENT ELECTRICITY / STROOMELEKTRISITEIT

I

VR = )rR(I)(emk +=ε

...rrrR 321 +++=

...r

1

r

1

r

1

R

1

321

+++= tIq ∆=

W = Vq W = VI ∆ t W= I

2R ∆ t

W= R

∆tV2

∆t

WP =

P = VI P = I2R

R

VP

2

=



ALTERNATING CURRENT / WISSELSTROOM/

2

II maxrms =

2

VV max

rms =

R

VP

RIP

IVP

2

rmsave

2

rmsave

rmsrmsave

=

=

=

PHYSICAL SCIENCES: PHYSICS (P1) · Title: Microsoft Word - WKP KWOD PHYSC P1 Sept 2014 ENG Author:...

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