[Edu.joshuatly.com] Pahang STPM Trial 2010 Physics [w Ans] [9C9EAE7A]

SULIT

960/1

SEPTEMBER 2010

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PELAJARAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

PHYSICS

PAPER 1

One hour and fourty-five minutes Instructions to candidates:

DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO.

There are fifty questions in this paper. For each question, four suggested answers are given. Choose one correct answer and indicate it on the multiple-choice answer sheet provided.

Read the instructions on the multiple-choice answer sheet very carefully.

Answer all questions. Marks will not be deducted for wrong answers.

A Data Booklet is provided.

Arahan kepada calon:

JANGAN BUKA BUKU SOALAN INI SEHINGGA ANDA DIBENARKAN BERBUAT DEMIKIAN.

Ada lima puluh soalan dalam kertas ini. Bagi setiap soalan, empat cadangan jawapan diberikan. Pilih satu jawapan yang betul dan tandakan jawapan itupada helaian jawapan aneka pilihan yang dibekalkan.

Baca arahan pada helaian jawapan aneka pilihan itu dengan teliti.

Jawab semua soalan. Markah tidak akan ditolak bagi jawapan yang salah.

Buku Data dibekalkan.

http://edu.joshuatly.com/ http://www.joshuatly.com/

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960/1 [Turn over *This question paper is CONFIDENTIAL until the examination is over. CONFIDENTIAL *

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1. The ideal gas equation is given by

pV = nRT

where p is the gas pressure, V is the volume of gas, n is the number of moles and T is the thermodynamics temperature. What is the dimension of molar gas constant, R? A M L2 T-1 θ-1 B M2 L2 T-2 θ-1 C M L2 T-2 N-1 θ-1 D M L T-2 N-3

2. When a force F varies as shown in the diagram below acts on a 10 kg of mass, the change in momentum is 40 kg m s-1.

What is the value of x? A 4 B 8 C 10 D 15 3. The diagram below shows three bodies of masses 5 kg, 10 kg and 20 kg connected by two light inelastic strings. The bodies are pulled by a force F = 700 N on a smooth surface.

What are the tension in the string T1 and T2 ? T1 T2

A 400 N 600 N B 600 N 400 N C 200 N 800 N D 800 N 200 N

5 kg F

Smooth surface

10 kg 20 kg T1 T2

F/N

t/s 2 5

x

1 3 4 0


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4. The engine power of a car of mass m is P. What is the minimum time taken for the car to accelerate from rest to a speed of v?

A2

P

mv B

2

2

mv

P C

2

2P

mv D

2mv

P

5. The figure below shows a pendulum bob with mass m hung on a light inelastic string from the point O and is whirled with speed v in a horizontal circle of radius r.

The string is inclined at angle θ with the vertical. If the tension in the string is T, what is the centripetal force for the horizontal circular motion? A θsinT

B 2

sinmv

Tr

θ +

C θcosT

D 2

cosmv

Tr

θ +

6. A bicycle wheel of radius 0.2 m rotates freely about a fixed axis. A constant force of 3 N is applied tangentially to the wheel for 0.4 s. The wheel starts to rotate from rest and its moment of inertia about the axis of rotation is 0.5 kg m2. What is its angular velocity after 4.0 s?

A 0.12 rad s-1 B 0.48 rad s-1 C 1.20 rad s-1 D 1.60 rad s-1 7. Which of the following will not influence the moment of inertia of a rigid body?

A Mass

B Shape

C Axis of rotation

D Angular frequency

θ

O

v

m r


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8. The diagram below shows a wooden block rest on an inclined plane. The mass of the block is m and the coefficient friction between the block and the plane is µ. Find the maximum angle θ between the inclined plane and the horizontal plane if the block does not slides down.

A tan-1(mg) B tan-1(mg

µ) C tan-1(

mg

µ) D tan-1 µ

9. Two point masses m and M are separated by a distance d. The gravitational force between them is F. If the distance between the masses is increased to 4d. What is the gravitational force between them?

A 4

F B 4F C

16

F D 16F

10. The diagram below shows a tunnel through the centre of the Earth, O from point X to point Y.

Assuming that that Earth is a uniform sphere, which of the following graphs represent the variation in the gravitational field strength, E from X to Y?

A B

C D

m

θ

X Y

O

E

d X O Y

E

d X O Y

E

d X O Y

E

d X O Y


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11.The diagram below shows a mass-spring system on a horizontal smooth surface. The body with mass m undergoes simple harmonic motion with constant amplitude of 5.0 cm and total energy of 20 J.

What is the magnitude of the displacement from the point of equilibrium when the kinetic energy of the system is 10 J? A 1.41 cm B 2.24 cm C 2.50 cm D 3.54 cm

12. A particle of mass m is in simple harmonic motion with amplitude A. The total energy of the particle is E. The period is given by

A 2mA

Eπ B

22

E

mAπ C

2

22

mA

Eπ D

2

22

E

mAπ

13. Which of the oscillations below will come to rest earlier? A free oscillation B under damped oscillation C critically damped oscillation D over damped oscillation

14. A progressive wave is represented the equation

s = 0.05 cos (50πt -1

4πx)

where s is the displacement in metre, x is the distance in metre and t is the time in second. What is the speed of the wave? A 20 m s-1 B 40 m s-1 C 100 m s-1 D 200 m s-1 15. Two progressive waves which have the same frequency, speed and amplitude, propagate in opposite direction are represented by

y1 = a cos (ωt - φ)

y2 = a cos (ωt + φ)

The superposition of the two waves produces a stationary wave. The intensity of the stationary wave is directly proportional to A a2 cos2 φ B a2 sin2 φ C a cos φ D a sin φ 16. An open-end pipe has length of 40.0 cm. The end correction at each end is assumed to be 0.8 cm. Find the frequency of the fundamental note if the speed of the sound is 300 m s-1. A 361 Hz B 371 Hz C 381 Hz D 391 Hz

m

Smooth surface

Wall


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17. The variation of the intermolecular force F with the separation r between two molecules is shown in the graph below.

Which statement about the situation at point P is true?

A The potential energy is minimum B The molecule is in a state of equilibrium C The force is a repulsive force and in its weakest state D The force is an attractive force and in its strongest state

18. The potential energy V between two molecules is given by

9

a bV

r r= −

where a and b are constant, r is the separation between two molecules. What is the equilibrium separation between the molecules?

A

1

8

9

a

b

B

1

89a

b

C

1

89b

a

D

1

8

9

b

a

19.A wire has original length l, cross-sectional area A, force constant k, and Young’s modulus E. Find Young’s modulus E in the expression of k, A and l.

A kA

l B

Al

k C

kl

A D

A

kl

20. What is the r.m.s. speed of the molecules of helium gas at 27 oC? [Molar mass of helium is 4.00 g mol-1] A 410 m s-1 B 456 m s-1 C 789 m s-1 D 1370 m s-1 21. Which of the following influence the degree of freedom of a gas molecule?

A The number of atoms per molecule and the temperature of the gas. B The mass of the gas molecule and the temperature of the gas. C The mass of the gas molecule and the pressure of the gas. D The r.m.s. speed of the gas molecule and the pressure of the gas.

P


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22. An ideal gas is expanded at constant pressure, then cooled at constant volume, and finally compressed adiabatically until it is returned to its original state. Which graph shows the changes which occur to the gas?

23. One mole of ideal gas is compressed isothermally at 400 K from the volume of V to 1

4V . The

work done on the gas is

A 2.0 kJ B 3.3 kJ C 4.2 kJ D 4.6 kJ 24.If the flow of current is compared to the flow of heat in a conductor, the electrical conductivity is analogous to the thermal conductivity. What is the temperature analogous to? A electric potential

B electric field intensity

C current density

D charge density

25. A container has a total surface area of 0.004 m2 with an average thickness of 0.8 cm. The temperature of the outside and inside surface is 90 oC and 32 oC respectively. What is the time needed to melt 24 g of ice? [Thermal conductivity of the container = 0.8 W m-1 K-1, specific latent heat of fusion of ice = 3.34 x 105 J kg-1] A 315.5 s B 320.3 s C 341.2 s D 345.5 s


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26. When paint-spraying a car, a potential difference may be applied which sets up an electric field between the spray gun and the car. The paint droplets emerge from the spray gun carrying a charge. Which of the following situations would increase the chance of paint droplets reaching the car ? Potential of Potential of Charge on spray gun car droplets A positive zero negative B negative zero negative C negative positive positive D positive positive positive 27. The diagram below shows two metal spheres X and Y which are placed close to each other but not in contact. X is negatively charged and Y is earthed.

Which of the following is correct for Y ? Charge on Y Electric potential on Y A Zero Zero B Negative Positive C Positive Zero D Negative Negative 28. A capacitor discharges through a resistance wire with time constant τ1. When the wire is replaced by another wire of the same material and length but double the diameter, the time constant is τ2. What is the ratio of τ2 : τ1 ? A 1: 4 B 1 : 2 C 2 : 1 D 4 : 1 29. Three resistors are connected as shown in the diagram using connecting wires of negligible resistances.

What is the resistance between points P and Q ? A 0.5 Ω B 0.8 Ω C 2.0 Ω D 3.6 Ω

1.0 Ω 2.0 Ω 3.0 Ω P Q

X Y


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30.An electric current flows along an insulated strip PQ of metallic conductor. The current density in the strip varies as shown in the graph below.

Which one of the following statements could explain this variation ? A The current at P is greater than the current at Q. B The potential gradient along the strip is uniform. C The strip is narrower at P than at Q. D The resistance per unit length of the strip is constant. 31. The diagram below shows four parallel wires vertically through the four vertices of a square WXYZ. These wires carry currents of equal magnitudes in the direction shown.

The direction of the resultant magnetic field at the centre O of the square is A OM B ON C OP D OQ

W X

X

X Y

M

N

P Q

Z

O

Current density

Distance along strip from P P Q


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32. If a stationary electron is subjected to a uniform magnetic field, it will be : A accelerate in the direction of the field B caused to move in a circular path C caused to oscillate about a fixed point. D unaffected. 33. When the load of an electric motor is increased, the speed of rotation of the motor decreases while the current that flows through it increases. Which of the following statements explains the increase in the current ? A The resistance of the coil of the motor decreases. B The power dissipated in the coil of the motor decreases. C The back emf induced in the coil of the motor decreases. D The voltage supplied to the motor increases. 34. A long straight wire XY lies in the same plane as a square loop of wire PQRS which is free to move. The sides PS and QR are initially parallel to XY. The wire and loop carry steady currents as shown in the diagram below.

What will be the effect on the loop ? A It will move towards the long wire. B It will move away from the long wire. C It will rotate about an axis parallel to XY. D It will be unaffected. 35. A steady current I dissipates a certain power in a variable resistor. The resistance has to be halved to obtain the same power when a sinusoidal alternating current is used. What is the r.m.s. value of the alternating current ?

A 2

1I B I C 2 I D 2 I

X

Y

P Q

R S


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36. An alternating current I which flows through a 5 Ω resistor is given by I = 4 sin(50t). If I is in amperes and t in seconds, what is the mean power generated in the resistor? A 5 W B 20 W C 40 W D 80 W 37. In the circuit shown in the diagram, the operational amplifier may be assumed to be ideal. The current in the in the 12 kΩ resistor is I.

What is the current If in the 72 kΩ resistor ?

A 0 B 6

1I C I D 6 I

38. In which part of the electromagnetic spectrum does a wave of frequency 500 MHz occur? A infra-red B radio C ultra-violet D visible 39. What is the focal length of a drop of water in the form of a sphere with radius

4 mm? [ The refractive index of water = 3

4]

A 2 mm B 4 mm C 6 mm D 8 mm 40. An object is placed 20 cm from a concave mirror with radius of curvature of 10 cm. The image formed is A 6.7 cm in front of the mirror and is diminished. B 6.7 cm behind the mirror and is enlarged. C 10.0 cm in front of the mirror and is diminished. D 10.0 cm behind the mirror and is enlarged.

12 kΩ

72 kΩ

I If _

+


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41. The diagram below shows the arrangement of Young’s double-slit experiment. S is the monochromatic light source of wavelenth λ. The centre of the interference pattern which is produced on the screen is located at O with OS being perpendicular to the two slits S1 and S2. P is the location of the second dark band.

Which of the following is true about the optical path difference between S1P dand S2P?

A λ2

1 B λ C λ

2

11 D λ2

42. The diagram below shows a beam of unpolarised light of intensity Io which passes through polarisers P1 and P2.

The intensity of the light after passing through P2 is

A Io8

1 B Io

4

1 C Io

8

3 D Io

4

3

Io

Unpolarised beam

Direction of polarisation

P1

P2

45o

P

O S S1

S2


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43. A parallel beam of white light is incident normally on a diffraction grating. The second-order and the third order fringes partially overlap. Find the wavelength in the third-order spectrum that appears to be at the same angle as the wavelength of 600 nm in the second-order spectrum. A 200 nm B 300 nm C 400 nm D 900 nm 44. In a photoemission experiment, the wavelength of the light incident on the target material is increased. What is the effect of this change of wavelength on the photoelectrons produced ? A The number of photoelectrons produced increases. B The number of photoelectrons produced decreases. C The maximum kinetic energy of the photoelectrons decreases. D The maximum kinetic energy of the photoelectrons increases. 45. Which of the following is correct for the kinetic energy E and momentum p of a particle of de Broglie wavelength ? Energy Momentum

A λ

hcE =

λ

hp =

B 2

2

1mvE =

λ

hp =

C λ

hcE =

c

Ep =

D 2

2

1mvE =

c

Ep =

46. Listed below are five phenomena connected with photons and / or charged particles.

1. alpha-particle emission 2. beta-particle emission 3. line emission spectra 4. line absorbtion spectra 5. electron diffraction

Which of these phenomena give direct evidence for the existence of discrete electronic energy levels in atoms ? A 1 and 5 only B 2 and 3 only C 3 and 4 only D 1,2,3,4 and 5 47. A hydrogen atom is in the ground state. If the mass of the electron is m, the radius of its orbit is r, and h is Planck’s constant, which of the following is the expression for the angular momentum of the electron?

A π2

h B 2mr C

πm

h

2 D hmr 2


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14

48. A photon of X-ray of the minimum wavelength is produced by the A deceleration of electrons by the target atoms B removal of an electron in an inner shell of a target atom C loss of all the kinetic energy of an electron in a single collision with a target atom D elastic collisions between electrons and the target 49. What is meant by population inversion in laser production? A There are more atoms in the ground state than in the excited state. B There are more atoms in the excited state than in the ground state. C Excited-state atoms are equal in number with ground-state atoms. D Ground-state atoms become excited-state atoms by absorption of photons. 50. All the following statements describe how a lepton differs from a hadron, except A Lepton is an elementary particle. B Lepton does not experience strong force. C Lepton is always lighter than hadron. D Lepton experiences weak force.


NAMA:……………………………………………………………….

SULIT

960/2

SEPTEMBER 2010

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PELAJARAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

PHYSICS

PAPER 2

Two and a half hours

Instructions to candidates:

Answer all the questions in Section A in the spaces provided. All working must be shown. For calculations, relevant values of constants in the Data Booklet must be used. For numerical answers, units must be quoted wherever they are appropriate.

Answer any four questions from Section B. For this section, write your answers on the answer sheets provided. Begin each answer on a fresh sheet of paper, and arrange your answers in numerical order. Tie your answer sheets to this booklet.

Answers may be written in either English or Malay. A Data Booklet is provided.

Arahan kepada calon:

Jawab semua, soalan dalam Bahagian A dalam ruang yang disediakan. Semua kerja mestilah ditunjukkan. Bagi penghitungan, nilai pemalar yang berkaitan dalam Buku Data mestilah digunakan. Bagijawapan berangka, unit mestilah dinyatakan di mana-mana yang sesual

Jawab mana-mana empat soalan daripada Bahagian B. Untuk bahagian ini, tulis jawapan anda pada helaian jawapan yang dibekalkan. Mulakan setiap jawapan pada helaian kertas yang baru, dan susunjawapan anda mengikut tertib berangka. Ikat helaian jawapan anda bersama dengan buku soalan ini.

Jawapan boleh ditulis dalam bahasa Inggeris atau bahasa Melayu. Buku Data dibekalkan.

TINGKATAN:…………

For examiner's use

(Untuk kegunaan

pemeriksa)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Total (Jumlah)


CONFIDENTIAL*

960/2 [Turn over *This question paper is CONFIDENTIAL until the examination is over. CONFIDENTIAL*

2

Section A [ 40 marks ] Answer all questions in this section

1. a) Define systematic error , ……………………………………………………………………………………………… ……………………………………………………………………………………………… [ 1 mark ] b) A horizontal force of 20 N acts on an object of mass 2 kg on a smooth inclined plane as shown in diagram below. Find the magnitude of the resultant force acting on it ?

[ 4 marks ]

300

20 N


CONFIDENTIAL*


3 2. The diagram below shows a brick sliding along a roof inclined to the horizontal at an angle of 30 0 . A frictional force of 0.50 N acts on the sliding brick . The brick of mass 0.30 kg slides a distance of 4.0 m before falling off the roof. The edge of the slope is 5.8 m from the ground

Determine ,

a) the speed of the brick before it falls freely, [ 3 marks ]

b) the time taken for the free fall,

[ 2 marks ]

4m

5.8 m

300


CONFIDENTIAL*


4 3. Diagram (a) below shows a particle A moving with velocity u along OP , colliding elastically with another particle B of equal mass.

Initially B is stationary . After collision it moves off at angle θ to the horizontal with velocity w. A moves off with an angle α to the horizontal with velocity v as shown in diagram (b) above.

a) By applying the principle of conservation of momentum , show that resultant velocity, VR = u

[ 2 marks ]

b) Write an equation related to the elastic collision of the particles.

[ 2 marks ]

c) Show that θ + α = 900. [ 1 mark ]

A B

u

P

Diagram ( a ) Diagram ( b )

B

v

w

O α

θ

A


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5 4.A swing consists of a 14 kg rubber tyre suspended from a rope of length 6.0 m as shown in the diagram below . A child of mass 35 kg sits on the swing . The speed of the child at the lowest point is 4.0 ms -1.

Determine , a) the centripetal acceleration of the child at this lowest point,

[ 2 marks ]

b) the tension T in the rope at this lowest point,

[ 3 marks ]


CONFIDENTIAL*


6 5. +Q a ----- --------------------------------------------------------------------------------------- P O a +Q Two point charges, each of charge + Q, are placed at a distance 2a from each other in a vacuum. When a particle of mass M and charge - q is released from infinity, the particle moves along the direction PO as shown. Show that the maximum velocity attained by the particle is

Ma

Qq

0πε

[ 5 marks ]


CONFIDENTIAL*


7 6. A search coil which has 50 turns, each of diameter 5.0 cm, is placed with its plane perpendicular to a uniform magnetic field of 2.0 T. The search coil is connected to a sensitive galvanometer. The time taken to turn the coil through 900 so that its plane is parallel to the magnetic field is 0.2 s. Calculate, (a) the mean e.m.f. induced in the coil, [ 2 marks ] (b) the induced charge if the resistance in the circuit is 5 Ω .

[ 3 marks ]


CONFIDENTIAL*


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7. (a) The de Broglie wavelength of an electron is 5.0 nm. What is the kinetic energy of the electron ?

[ 2 marks ]

(b) Calculate the momentum of a photon having the same energy as the kinetic energy the electron in (a) above [ 3 marks ]


CONFIDENTIAL*


9

8. (a) The half-life of a certain radioactive nuclide is such that 16

15 of a given

sample decays in 8 days. What fraction remains undecayed after 10 days ? [ 2 marks ]

(b) A radioactive isotope at time , t ,has an activity of 1000 Bq. After 2 hours its activity dropped to 500 Bq. If the initial mass of the sample is 40 g, calculate the remaining mass of the sample after 3 hours.

[ 3 marks ]


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10

Section B [ 60 marks]

Answer any four questions in this section. 9 (a) Define simple harmonic motion. [2 marks]

(b) The diagram below shows the motion of a simple pendulum. Show that the

motion of the simple pendulum is simple harmonic. State any assumptions

made.

[5 marks]

Hence, deduce that the period of oscillation of the pendulum is given by

g

lT π2= [1 mark]

where l is the length of the pendulum and g is the gravitational field

strength.

(c) The graph below shows how the kinetic energy of a simple pendulum

varies with displacement.

(i) Sketch a graph to show how the potential energy of the pendulum

varies with displacement. [2 marks]

(ii) State the amplitude of the oscillation. [1 mark ]

l- length of string m- mass of bob

θ


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(iii) The frequency of vibration of the pendulum is 3.5 Hz. Write down

the equation that models the variation of position with time for the

simple harmonic motion of this pendulum. [1 mark]

(iv) Calculate the maximum acceleration of the simple pendulum.

[2 marks]

(v) State the value of the total energy of the system. [1 mark ]

10 (a) State the conditions required for a rigid body to be in equilibrium.

[2 marks]

(b) The diagram below shows a student standing on a plank that pivots on a

log. The student intends to cross the stream.

The plank has a mass of 20 kg and is 3.0 m long with a uniform cross-

section. The log pivot is 0.50 m from the end of the plank. The student has a mass

of 75 kg and stands at the end of the plank. A load is placed on the far end in order

to balance the plank horizontally.

(i) Draw on diagram above the forces that act on the plank. [3 marks]

(ii) By taking moments about the log pivot, calculate the load, in N, needed

on the right-hand end of the plank in order to balance the plank horizontally.

[3 marks]

(iii) Explain why the load will eventually touch the ground as the student

walks towards the log. [2 marks]


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(c) The diagram below shows three coplanar forces in equilibrium.

Find the value of P and of Q. [5 marks]

11 (a) (i) Sound wave is a longitudinal wave. What is meant by longitudinal

wave? [ 2 marks]

(b) A point source is emitting sound waves with a power of 2.0 μW.

(i) What is the intensity of the wave at a point 3.0 m away from the source?

[3 marks ]

(ii) What is the intensity level of sound at the point mentioned in

(b) (i) above? [3 marks]

( Minimum intensity of sound that can be heard is 1.0 x 10-12 W m-2 )

(c) Beats are produced at a point when two sound waves meet.

(i) What is meant by beats. [2 marks]

(ii) State two conditions necessary for the formation of beats.

[2 marks]

(iii) If the frequency of the waves are 800 and 825 Hz respectively,

(a) Determine the beat frequency. [2 marks]

(b) Calculate the frequency of the resultant wave [1 mark ]

400 200

Q N

P N 20 N


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12 (a) State two functions of the dielectric in a capacitor. [2 marks]

(b) Two pure capacitors of capacitance C1 = 5.0 μF and C2 = 10.0 μF are connected in

series to a 10.0 V battery.

(i) Derive an expression for the effective capacitance CT of the circuit and calculate

the value of CT. [4 marks]

(ii) Calculate the total energy stored in the circuit. [2 marks]

(c) The battery in (b) is replaced by an alternating current supply of maximum voltage

10 V and frequency 120 Hz.

(i) Calculate the reactance of the combined capacitor. [2 marks]

(ii) Calculate the maximum current in the circuit. Comment on the phase of the

current with reference to the voltage supplied. [3 marks]

(iii) Describe briefly the behavior of the energy stored in the combined capacitor

during a cycle of the alternating current supply. [2 marks]


PHYSICS / TRIAL STPM / 2010

13. The diagram below shows an inverting amplifier circuit using an ideal operational amplifier. R1 is an input resistor and R2 a feedback resistor.

(a) What is meant by negative feedback? [1 mark]

(b) State two advantages of negative feedback. [2 marks]

(c) (i) Explain why point P in the above circuit is known as a virtual earth.

[2 marks]

(ii) Derive an expression for the voltage gain of the above inverting amplifier

circuit. [3 marks]

(d)

(i) If R1 = 2.0 kΩ, R2 = 10.0 kΩ, and input voltage Vi is as shown in the graph

above, sketch a graph to show how output voltage V0 varies with time for the

inverting amplifier above . Indicate the value of the maximum voltage on your

graph. [3 marks]

R2


PHYSICS / TRIAL STPM / 2010

(ii) If R1= 2.0 kΩ, R2 = 20.0 kΩ, sketch a graph of output voltage V0 against

time for the inverting amplifier above.

State the advantage of selecting a small value of voltage gain. [4 marks]

14 (a) (i) Define the stopping potential in photoelectric effect. [1 mark]

(ii) State four most important results from a photoelectric effect experiment.

[4 marks]

(b) The work function for caesium is 2.14 eV.

(i) Calculate the maximum wavelength of light that ejects electrons from a caesium

target.

[3 marks]

(ii) If light of wavelength 452 nm is illuminated on caesium, calculate the maximum

kinetic energy of photoelectrons.

[2 marks]

(c) If this page of this question paper is illuminated by 120 W m-2 of light with

wavelength 550 nm, calculate

(i) the power received by an area of 1.0 cm2, [2 marks]

(ii) the number of photons striking each square centimetre per second.

[3 marks]


Skema Pemarkahan Peperiksaan Percubaan Pahang 2010

Physics STPM Paper 1

Question Answer Question Answer 1 C 26 B 2 C 27 D 3 A 28 A 4 B 29 A 5 A 30 C 6 B 31 B 7 D 32 D 8 D 33 C 9 C 34 A

10 B 35 C 11 D 36 C 12 C 37 C 13 C 38 B 14 D 39 C 15 A 40 A 16 A 41 C 17 D 42 B 18 B 43 C 19 C 44 C 20 D 45 A 21 A 46 C 22 C 47 A 23 D 48 C 24 A 49 B 25 D 50 C


Marking scheme 1. Systematic errors are uncertainties in the measurement of a physical quantity due to instruments , physical conditions of the surrounding or physical limitations of the observer . …………………………. ………………………………………………. 1m

R = 20 sin 300 + 19.6 cos 300 ……………………………………….1m

Net force = 20 cos 300 - 19.6 sin300 ………………………………………1m = 17.3 – 9.81 ………………………………………………………………...1m

= 7.49 N …………………………………………………………………1m 2. a) Net force downwards , mg sin θ - Ff = ma ( 0.30 x 9.81 x sin 300 – 0.50 ) = 0.30 a .............................................1m a = (1.47 - 0.5 ) / 0.30 = 3.23 m s-2

Using v2 = u2 + 2as = 0 + 2 (3.23) (4) ………………..1m v = 5.09 m s-1 …………………1m

b) s = ut + ½ gt2

5.8 = ( 5.09 x sin 30 ) t + ½ ( 9.8 ) t2 …………………………………1m 5.8 = 2.545 t + 4.91 t2

t = 0.8607 s …………………………………1m


3. a) Initial momentum = mu Final momentum = mu + mw ............................1m mu = mu + mw = mVR ..........................1m u = VR

b) ½ m u2 = ½ m v2 + ½ m w2 …………………………1m u2 = v2 + w2 ………………………….1m c)

4.i) a = v2 / r = 4.02 / 6.0 ………………………………………………1m = 2.67 m s-2 ………………………………………………..1m ii) total mass , m = 35 + 14 = 49 kg T – mg = ma T = mg + ma ………………………….1m = 49 x ( 2.67 + 9.8 ) ………………………1m = 611 N …………………………..1m

u

w α

α

θ

θ

v

Pythagoras Theorem ………………1m


5 Electric potential at O V = 2Q / 4лε0a ………………………...

1m

Electric potential energy at O to bring –q from infinity U = 0 – 2Q(-q) / 4лε0a ……………………………... = 2Qq/4лε0 = Qq / 2лε0 ……………………………………………

1m 1m

½ Mv2 = Qq/2лε0 , .....……….………………… v = (Qq/лε0Ma)1/2 ... ……………………………

1m 1m

6 (a) E = ( NBA – 0 ) / 0.2

= 50 x 2.0 x л x (2.5 x10-2 )2 / 0.2 ....................... = 0.982 V ……………………….

1m 1m

(b) E = ( NBA -0 ) / t = IR = ( Q/t) R ..................................... Q = 50 x 2.0 x л x (2.5 x10-2)2 /5 .......................... = 0.0393 C .....................................

1m 1m 1m

7. (a) mv = p = h / λ V = h / m λ = 6.63 x 10-34 / 9.11 x 10-31 x 5.0 x 10-9 = 1.46 x 105 m s-1 ………………..

1m

Kinetic energy = ½ ( 9.11 x 10-31 ) x (1.46 x 105 )2 = 9.71 x 10-21 J ………......................

1m

(b) E = h f = h c/ λ λ = 6.63 x 10-34 x 3 x 108 / 9.71 x 10-21 .........................

= 2.05 x 10-5 m .................................

1m 1m


p = h / λ = 6.63 x 10-34 / 2.05 x 10-5 = 3.23 x 10-29 kg m s-1 .............

1m

8 (a) 1 – 1 / 16 = 1 - 1 / 24 = 15 / 16

4 half –lives = 8 days , T1/2 = 2 days ………... Fraction remains after 10 days is ( ½ )5 = 1 / 32 ……...

1m 1m

(b) T1/2 = 2 hrs = ln 2 / λ …………………………....... λ = 0.347 hr -1

M = M0 e –λt M = 40 e-0..347 x 3 ………………………………

= 14.1 g ………………………………

1m 1m 1m


l- length of string m- mass of bob x- displacement

θ

x

θ

mgsinθ

9 (a) Acceleration is directly proportional to its displacement from a fixed point

and is always directed towards that fixed point. ………………………….2

(b)

-mg sin θ = ma ..……………………. 1

Since θ is very small, sin θ = θ, ……… 1

- mg θ = ma ………………………..

a = - g θ

= - g x

l , x = l θ ……………………………… 1

a = g

l− x ……………………………………………………1

Assumption : 1. amplitude of oscillation is small / oscillation in a

single vertical plane ………………………………… 1

ω2 = g

l ……………………………………………………. 1

or T = 2π

ω ……………………………………………………….1

(c)

(i) Correct shape ……………………………. …………………….. 1


Correct value …………………………………………………….1

(ii) 0.044 m ………………………………………………………….. 1

(iii) x = 0.044 sin (2π(3.5)t ) or x = 0.044 cos (2π(3.5)t ) etc …………..1 ecf for A

(iv) a = ( 2π(3.5))2 (0.044) …………………………………………..1

= 21.28 ms-2 ……………………………………………………1

(v) 2 x 10 -2 J ……………………………………………………1

10 (a) 1. Resultant force = 0 …………………………………………1

2. Resultant torque = 0 …………………………………………1

(b) (i) 1. Weight of person + load marked vertically down ……………… 1

2. Weight of planked marked at centre downwards …………………. 1

3. Upward force at pivot marked ……………………………………. 1

(ii) clockwise moment = anticlockwise moment …………………………1

75g (0.5) = 20g (1) + F (2.5) …………………………1

F = 68.67 N …………………………1

(ii) 1. anticlockwise/student moment becomes smaller …………...1 2. clockwise moment now larger than anticlockwise moment So plank rotates clockwise ………………………………………….1

(c) Resolving P into vertical & horizontal component

or Resolving 20 N force into vertical & horizontal component …………….1

P cos 40 = 20 cos 20 ………………………………………………….1

P = 24.53 N ………………………………………………… 1

Q = P sin 40 + 20 sin 20 ……………………………………………… 1

Q = 22.61 N ………………………………………………….. 1


11 (a) (i) Particle of waves vibrate parallel to the direction of propagation of waves.

………………………..2

(b) (i)

(ii)

(c) (i) 1. Superposition of two sound waves……………………………………..1

2. Resulting in periodic increase and decrease in the intensity of sound….1

(ii) 1. Two waves of slightly different frequency……………………………..1

2. Amplitude of the two waves are equal or differ slightly. …………………1

(iii) (a) Frequency of beats = f1 – f2 ………………………………………….1

= 825 – 800

= 25 Hz …………………………………………..1

(b) Frequency of resultant wave = ½ ( f1 + f2 )

= ½ ( 800 + 825 )

= 812.5 Hz ……………………… .. 1

6

2

8 2

....................1

2 10................1

4 (3)

1.769 10 ............1

PI

A

x

x Wm

π

−

− −

=

=

=

8

12

log .....................1

1.769 10log .......1

1 10

4.248 ...............1

o

IL

I

x

x

B

−

−

=

=

=


12 (a) two functions of the dielectric in a capacitor.

• To increase the storage of charges / energy • To increase the capacitance of capacitor • Can tolerate stronger electric field without break down

(any two) …………………………………..2 (b) (i)

Q = CV ………………………………. 1 VT = V1 + V2 .……………………………… 1

21

111

CCCT

+= ……………………………….. 1

µµ 10

1

5

11+=

TC

CT = 3.33μF ……………………………........ 1

(ii) Energy stored = 2

2

1TTVC

……………………………….. 1

= )10)(33.3(2

1 2Fµ

= 1.67 x 10-4 J ……………………………….. 1 (c) (i)

Xc =TfCπ2

1 ……………………………….. 1

= 398 Ω ……………………………….. 1 (ii)

Io =c

o

X

V

………………………………… 1

=389

10

= 0.025 A ………………………………… 1

The current leads the voltage by 90o or 2

πrad …………. 1

(iii) For 1st quarter, capacitor is charged, energy is stored in capacitor …………… 1 2nd quarter, capacitor is discharged, energy is returned to the source …………… 1 or For 3rd quarter, capacitor is charged, energy is stored in capacitor 4th quarter, capacitor is discharged, energy is returned to the source


13. (a) Part of the output voltage is applied to the negative / inverting input

of the amplifier …………………….1

–Voltage gain can be fixed / does not depends on the characteristic of the

ideal amplifier

-Voltage gain is constant for a wider frequency.

-Amplification is more stable or less distortion (any 2) ………………..2

(c) (i)

0=pV ………………………………………….. 1

++ =≈− VVorVV Pp ................0

or open loop gain is very high. ……………………..………………… 1

(ii) IRV =

for 1R 110 RIVi =−

or 2R 2200 RIV =− ……………………………………………… 1

21 II = because current flowing into terminal 0≈−

Or high input impedance …………………………………………………1

Voltage gain 1

20 )(R

R

V

V

i

−= ………………………………………………….1

(d) (i) Voltage gain = ( ) ( ) 0.50.2

0.10−=−

………………………………………….. 1


( )

V

V

5.7.....

5.15

−=

−=ο

………………………………………….1 Correct shape of graph ( antiphase ) …………………..…….1

a. Voltage gain = ( ) ( ) 0.100.2

0.20−=−

Or 15 V (marked on the graph) ………………………1

Shape of graph (antiphase) ………………………………1

Saturation +9V or -9V …………………………..1

Advantage:to avoid distortion …………… 1

7.5V

-7.5V

time


14 (a) (i)

The minimum potential required to stop the most energetic electron.

or

The minimum potential difference required to bring the current to zero

……………………..1

(ii) 1. When the intensity of the light is increased, the magnitude

of the (saturation) current increases.

2. When the intensity of the light is increased, the stopping potential remains constant 3. When the frequency of the light is increased, the stopping potential increases /the maximum kinetic energy of the electrons increases. 4. There exists a cut-off/threshold or lowest/minimum frequency below which no electron is ejected 5. The ejection of photoelectrons is immediate

(b) (i) W=hv or λ

hc 1

λmax = W

hc

= 19-

834

101.60 14.2

)1000.3)(1063.6(

××

×× −

1

= 5.81 × 10−7 m or 5.79 × 10-7 m

= 581 nm or 579 nm 1

(ii) Kmax = hv − W 1

= λhc

− W

= 197

834

106.11052.4

)1000.3)(1063.6(−−

−

×××

×× − 2.14 eV

Kmax = 2.75 eV − 2.14 eV

= 0.61 eV or 9.8 × 10-20 J 1

(Any four) 4 4 4


(c) (i) P = AI 1

= 120 × 1.0 × 10−4

= 1.2 × 10−2 W 1

(ii) E = λ

nhc 1

P = t

E 1

t

n =

hc

Pλ

= 834

72

1031063.6

105.510 2.1

×××

×××−

−−

= 3.3 × 1016 1


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[Edu.joshuatly.com] Pahang STPM Trial 2010 Physics [w Ans] [9C9EAE7A]