Stpm Physics Kedah 2007 P1

1

2007 Kedah Physics Paper 1 The dimensions of Young's modulus is A LT–2 B MLT–2 C ML–1T–2 D ML–2T–2

2 An object is thrown horizontally at a certain height above the ground. The graph of vertical velocity of the object (consider downward as positive) with time is

4 An object slides down an inclined plane passing through points A, B and C. Given that distance AB = 6 m and BC = 10 m, the object takes 2 seconds to move from A to B and also the same time from B to C. The instantaneous velocities of the ball at A, B and C are respectively A vA = 2 m s–1, vB = 3 m s–1, vC = 4 m s–1 –1 –1 B vA = 2 m s , vB = 4 m s , vC = 6 m s–1 –1 –1 C vA = 3 m s , vB = 4 m s , vC = 5 m s–1 –1 –1 D vA = 3 m s , vB = 5 m s , vC = 7 m s–1 5 A wooden block of mass m stays at rest on a smooth surface. From time t = 0 onwards, a constant horizontal force F is acting on the wooden block. What is the average power produced at time t = t1? A

F 2 t1 2m

B

F 2 t12 2m

C

F 2 t1 m

D

F 2 t12 m

6 A rigid body of mass m is considered to be made up of many small mass elements dm so that they are at a perpendicular distance r from the axis of rotation. The moment of inertia I of the body from the axis of rotation is given by A

3 The diagram below shows two wooden blocks of mass m1 and m2 respectively connected by two springs of negligible mass with spring constants k1 and k2 respectively. The whole system is in equilibrium. The wooden block on top is then slowly lifted upward until it is completely separated from the spring.

∫ mr

2

dr

B

∫ m dr

2

C

∫r

2

dm

D

∫ mr dr

7 A ball bearing P moves with a constant angular velocity ω along a horizontal circle of radius r = 10.0 cm inside an inverted cone of semi angle 35o as shown in the diagram below.

During this process, the bottom block is moved by a distance of A

m1 g k1

B

m2 g k1

C

m1 g k2

D

m2 g k2

What is the angular velocity ω of the ball bearing? A 1.4 rad s–1 B 8.3 rad s–1 C 11.8 rad s–1

D 20.5 rad s–1

8 Assuming the Earth to be a sphere, which of the following will happen if the Earth stops rotating about its own axis? A The weight of bodies on the equator will increase B All bodies will fly off from the Earth’s surface C The gravitational potential on the equator will increase D The acceleration of free fall at both North and South poles will decrease

11 The same progressive wave is represented by the following graphs.

9 The displacement x of a particle at time t is given by x = 5 sin 2t. A simple pendulum has the same period as this particle when the length of the pendulum is A 2.0 m B 2.5 m C 5.0 m D 10.0 m 10 A loaded spring has its upper end fixed to a variable frequency vibrator as shown in the diagram below.

Which of the following shows the speed of the wave? A pq

B

p q

C

q p

D

1 pq

12 Which of the following statements is not true about the phenomenon of beats produced by the superposition of two sound waves? A Frequencies of the waves differ slightly B Both waves propagate in the same direction C Amplitudes of the waves are nearly the same D Intensity of beats produced is twice the intensity of each individual wave The vibrator itself has constant amplitude. As the frequency of the vibrator is varied, the amplitude of vibration of the 150 g mass changes as shown in the graph below.

13 Tube X which is closed at one end and tube Y which has both ends open, have the same length. If the end correction can be neglected, what is the ratio of

frequency of the first overtone for tube X frequency of the first overtone for tube Y when air is blown across the open end of the tubes? A 1:4

B 2:3

C 3:2

D 3:4

14 The potential energy U between two atoms in a molecule is given by

U=

a b − 6 12 r r

where r is the separation between the two atoms and a and b are constants. The equilibrium separation between the two atoms is 1

Find the value of the spring constant. A 925 N m–1 B 950 N m–1

C l000 N m–1

D 1500 N m–1

6 A  a  b

1

6 B  b  a

1

6 C  2a   b 

1

6 D  b   2a 

15 If the level of intensity of sound is raised by 10 dB , what is the ratio of the new sound intensity to the original sound intensity? A 0.1 B 1 C 10 D 1010

22 Diagram below shows three capacitors connected between XY. A 12.0 V battery is applied across XY.

16 The fact that light is a transverse wave can be shown by A interference B polarization C Doppler effect D photoelectric effect 17 Which of the following will take place at the yield point for a wire when it is stretched by an increasing force? A Plastic deformation begins B The wire becomes thinner unevenly C The wire undergoes elastic deformation D The overall work done on the wire cannot be recovered 18 The speed for nine particles are tabulated as shown

The rms speed of the particles is A 1.2 m s–1 B 3.0 ms–1

C 3.3 m s–1

D 3.6 m s–1

19 The ratio of the molar heat capacity of an ideal gas is a. What is the number of degrees of freedom of the gas? A

2a a −1

B

a −1 2

C

a+2 a

D

2 a −1

20 Which of the following is true about the adiabatic expansion of an ideal gas? A The rms speed of the gas decreases B The internal energy of the gas increases C The temperature of the gas does not change D The external work done is more than the change in internal energy 21

What is the total force exerted on the point charge q3 by the other two point charges? A 28 N B 2.8 x 105 N C -2.8 x 10–5 N D -28 N

The potential difference across the 4 μF capacitor is A 6.67 V B 2.2 V C 22 V D 26.7 V 23 Two capacitors with capacitance C and 3C, are charged to a potential difference of V and 2V respectively. If the positively charged plates of the capacitors are connected and the negatively charged plates are connected too, the system of capacitors will experience A an increase in charge but a loss in energy B an increase in energy but a loss in charge C a loss in both energy and charge D a loss in energy but the charge remains constant 24 The diagram below shows a Wheatstone bridge. S is known to be 30 Ω. The circuit is balanced when a resistance of 150 Ω is connected directly across S. The positions of P and Q are exchanged and the resistance of 150 Ω across S is removed. The circuit is balanced again when a resistance of 380 Ω is connected directly across S. The ratio of P : Q is A 0.2 B 0.39 C 0.95 D 1.05 25 A moving coil meter of resistance 100 Ω indicates full-scale deflection when a current of 100 μA flows through it. If the meter is required to indicate full-scale deflection when a current of 1 mA flows in the circuit. the resistance of the shunt to be connected across the meter has to be A 9Ω

B 10 Ω

C

100 Ω 9

D 900 Ω

26 The diagram below shows an electric circuit. The potential difference between the points X and Y is A 10 V B 2.0 V C 3.0 V D 6.0 V

31 A toy car has a small electric motor whose armature has a resistance of 2.0 Ω. The motor is connected to a 12 V battery. A current of 2.0 A flows through the motor when the car runs at a constant speed of 1.0 m s–1. Determine the speed of the car when it runs up a slope and the current flowing through the motor is 5.0 A. A 0 m s–1

27 A galvanorneter which has a resistance of 2 Ω gives a full scaledeflection when a current of 1 mA flows through it. The galvanometer is being modified to measure currents up to several amperes. Which of the following modified arrangements is correct?

B 0.25 m s–1

C 0.70 m s–1

B 2.5 m s–1

32 An alternating current I / A varies with time t / s according to the equation I = 5 sin (100 π t) What is the mean power developed by the current in a resistive load of resistance 10 Ω? A 125 W B 160 W C 250 W D 500 W 33 The following are the advantages of negative feedback except A The voltage gain is very stable. B The voltage gain is greatly increased. C The bandwidth is greatly increased. D Distortions of signals are much reduced. 34 The following are true about electromagnetic waves except A Electromagnetic waves carry energy. B Electromagnetic waves transport linear momentum. C Electromagnetic waves exert pressure on surface. D Electromagnetic waves carry electric charge.

28 A beam of electrons moves in a straight path through a region which has uniform electric and magnetic fields. The electric field is produced by two parallel metal plates 35 The graph below shows the variation of image distance v against object distance u which are 4.0 m apart with a potential difference of 1000 V. If the speed of the 6 –1 for images formed by a lens. electrons is 2.5 x 10 m s , the magnetic flux density is –1 –2 –3 –4 It can be deduced from the graph that the lens is a ………….. lens and its focal A 1.0 x 10 T B l.0 x l0 T C l.0 x 10 T D l.0 x l0 T length is ………… cm. 29 Which of the following factors does not affect the magnetic flux density of the A converging, 7.5 magnetic field at the centre of a plane circular coil ? B diverging, 7.5 A The number of turns of the coil. C converging, 15.0 B The magnitude of the current flowing in the coil. D diverging, 15.0 C The diameter of the coil. D The thickness of the wire of the coil. 30 A coil rotating with constant angular velocity in a uniform magnetic field produces a sinusoidal alternating e.m.f. E. If the number of turns and the area of the coil are doubled, but the flux density and angular velocity are halved, the new induced e.m.f is A E B 2E C 4E D 16E

36 Which of the following statements concerning a virtual image produced by a mirror is true? A A virtual image is always larger than the object. B A virtual image is always smaller than the object. C A virtual image is always upright relative to the object. D A virtual image is always inverted relative to the object. 37 Light of wavelength λ in vacuum strikes a lens that is made of glass with refractive index 1.6. The lens has been coated with a film of thickness t and refractive index 1.3. Which of the following conditions will not produce reflection?

A

 λ  2t =    1.3 

B

 λ  2t =    1.6 

C

2t =

1 λ    2  1.6 

D

2t =

1 λ    2  1.3 

44 Which of the following describes correctly the changes, if any, in λmin and the intensity of the continuous X-ray spectrum if the potential difference of the X-ray tube is increased? A B C D

λmin Decreases Decreases Does not change Increases

Intensity of continuous spectrum Decreases Increases Increases Decreases

45 Which of the following is not a characteristic of lasers? A Highly divergent B Monochromatic C Coherent D High intensity 46

235 92

U decays through a series of transformations to a final stable nuclide. The particles

38 Two polarizing sheets have their transmission axes parallel so that the intensity of unpolarized light transmitted through both of them is maximum. Through what angle must either sheet be rotated if the transmitted intensity is 25% of the incident intensity? A 30o B 45o C 60° D 75°

emitted in the first five successive transformations are α, β, β, α and α. Which of the following nuclides is not formed during the transformations?

39 Light of wavelength 625 nm shines through a single slit of width 0.320 mm and forms a diffraction pattern on a flat screen located 8.00 m away. Determine the distance between the middle of the central bright fringe and the first dark fringe. A 0.516 cm B 1.56 cm C 5.16 cm D 6.51 cm

47 23 He is an isotope of helium. If the masses of a proton, a neutron and 23 He nucleus are equivalent to an energy of 938.3 MeV, 939.6 MeV and 2808.5 MeV respectively, the binding energy of 23 He is A 0 MeV B 7.7 MeV C 9.0 MeV D 930.6 MeV

40 Photons of energy 5.0 eV strike a metal with a work function of 3.5 eV. Determine which of the following best describes the kinetic energy of the emitted electrons. A 1 .5 eV or less B 1.5 eV or more C 3.5 eV or less D 3.5 eV or more 41 In an X-ray tube, electrons, each of charge q, are accelerated through an electric potential difference V and strike a metal target. If h is the Planck constant and c is the speed of light, the minimum wavelength of the X-ray produced is given by

A

hq cV

B

qV hc

C

qV h

D

hc qV

A

228 88

Ra

B

230 90

Th

C

234 91

Pa

D

234 92

U

48 In a controlled thermal fission reactor, the use of control rods will not affect A the speed of the neutrons released on fission B the rate of production of the neutrons C the energy generated in the nuclear reactor D the amount of radioactive radiations produced in the nuclear reactor 49 Isotope

40 19

K which has a half life of 1.3 x 109 years, decays to stable

in a sample were originally all 40 19

40 19

40 18

Ar . If the nuclei

K , approximately how many years would elapse before the

40 18

ratio of K to Ar is 1: 3 ? 42 There are three energy levels for a particular atom. In a transition from E3 to E2, ultraviolet A 0.4 x 109 B 2.0 x 109 C 2.6 x 109 radiation of wavelength 2.4 x 10–7 m is emitted. In another transition from E2 to E1, ultra-violet radiation of wavelength 8.0 x l0–8 m is emitted. What is the wavelength of the radiation 50 Which of the following forces has the shortest range? produced in transition from E3 to E1? A The weak nuclear force A 3.0 x 10–8 m B 6.0 x 10–8 m C 12.0 x 10–8 mD 16.0 x 10–8 m B The strong nuclear force C The gravitational three 43 According to Bohr’s postulates, which of the following quantities takes discrete values? D The electromagnetic force A Momentum B Angular momentum C Kinetic energy D Speed

D 3.3 x 109