MJC 2010 H2 Physics Prelim Paper 1

Preliminary Examination Meridian Junior College 24 September 2010

JC2 H2 Physics 2010

This document consists of 17 printed pages

MERIDIAN JUNIOR COLLEGE

Preliminary Examination Higher 2

___________________________________________________________________

H2 Physics 9646/1

Paper 1 24 September 2010

1 hour 15 mins

___________________________________________________________________ READ THESE INSTRUCTIONS FIRST

Class Reg Number

Candidate Name _____________________________ Do not open this booklet until you are told to do s o.

There are forty questions in this section. Answer all questions. For each question, there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the Optical Mark Sheet (OMS).

Read very carefully the instructions on the OMS.

Write your name and class in the spaces provided on the OMS.

Shade your Index Number column using the following format:

1) first 2 digits is your index number in class (e .g. 5th student is shaded as “05”); 2) ignore the last row of alphabets.

Preliminary Examination Meridian Junior College 24 September 2010 JC2 H2 Physics 2010

2

DATA AND FORMULAE Data speed of light in free space c = 3.00 x 108 m s-1

permeability of free space µo = 4π x 10-7 H m-1

permittivity of free space ε0 = 8.85 x 10-12 F m-1

= (1/(36π)) x 10-9 F m-1

elementary charge e = 1.60 x 10-19 C

the Planck constant h = 6.63 x 10-34 J s

unified atomic mass constant u = 1.66 x 10-27 kg

rest mass of electron me = 9.11 x 10-31 kg

rest mass of proton mp = 1.67 x 10-27 kg

molar gas constant R = 8.31 J K-1 mol-1

the Avogadro constant NA = 6.02 x 1023 mol-1

the Boltzmann constant k = 1.38 x 10-23 J K-1

gravitational constant G = 6.67 x 10-11 N m2 kg-2

acceleration of free fall g = 9.81 m s-2

Formulae uniformly accelerated motion

s = ut + 1

2at2

v2 = u2 + 2as

work done on/by a gas W = p∆V

hydrostatic pressure p = ρgh

gravitational potential φ = -Gm/r

displacement of particle in s.h.m. x = xo sin ωt

velocity of particle in s.h.m. v = vo cos ωt

= ± ω 2 2o -x x

resistors in series R = R1 + R2 + …

resistors in parallel 1/R = 1/R1 + 1/R2 + …

electric potential V = Q/4πεor

alternating current/voltage x = xo sin ωt

transmission coefficient T = exp(-2kd)

where k =

π −2

2

8 ( )m U E

h

radioactive decay x = xo exp(-λt )

decay constant λ

=

1

2

0.693

t


3

Answer all 40 questions in this paper and shade you r answers on the answer sheet provided. 1 The length of a rectangle is given as L ± l and its width as W ± w. What is the uncertainty

in its area? A l + w B L Ww + l C L Wl + w

D L W

+l w

2 For which quantity is the magnitude a reasonable estimate? A mass of an atom 500 pg B wavelength of green light 500 nm C frequency of a radio wave 500 µHz D the acceleration due to free fall 981 mm s-2

3 A housewife released a bag of rubbish weighing 54 N from rest into a refuse chute from

her unit in a HDB flat. The rubbish passes through two speed detectors at different locations and the readings shown in the detectors are 14.7 m s-1 and 49.1 m s-1 respectively. Neglecting the effect of air resistance, the distance between the two speed detectors is

A 20.3 m B 31.9 m C 71.7 m D 112 m 4 When a ball is thrown upwards at an angle to the horizontal with an initial speed.

Assuming that air resistance is not negligible, which of the following statement is incorrect?

A The path of the ball is asymmetrical about the highest point. B Horizontal range of the ball is shorter than the case with negligible air resistance. C The maximum height reached by the ball is smaller than the case with negligible air

resistance. D The time taken for the flight up to the highest point is longer than the time taken for the

flight down.


4

5 A car of weight Wc is driven across a uniform bridge of length l and weight Wb. The bridge is supported by two ropes having tensions T1 and T2 when the car is a distance x from the rope on the left as shown in the figure below.

Which of the following expressions for the tensions T1 and T2 is correct?

Tension T1 Tension T2

A 2

b cW W+

x

l (1 )

2b

c

WW+ − x

l

B 2

b cW W+

l

x (1 )

2b

c

WW+ − l

x

C 22

cb WW+

22cb WW

+

D (1 )2

bc

WW+ − x

l

2b cW W

+x

l

6 Three identical stationary discs P, Q and R are placed in a line on a horizontal, flat,

frictionless surface. Disc P is projected straight towards disc Q. If all consequent collisions are perfectly elastic, predict the final motion of the three discs.

P Q R A moving left moving left moving right B moving left stationary moving right C stationary stationary moving right D moving right moving right moving right

T2

x

Wc Wb

T1

l

P Q R


5

7 In the Pixar movie, Up, an old man lifted his house using about 20000 helium balloons. Assuming that the average volume of each balloon used is 0.17 m3, determine the weight of the old man’s house. (density of air = 1.2 kg m-3, density of helium = 0.18 kg m-3)

A 6000 N B 34000 N C 40000 N D 46000 N 8 A sphere of mass 3.00 kg rests on a frictionless slope inclined at 300 above the horizontal

as shown below. The spring constant is 500 N m-1. Determine the compression of the spring.

A 7.67 mm B 29.4 mm C 34.3 mm D 51.0 mm 9 A small metal sphere of mass m is moving through a viscous liquid of height h. When it

reaches a constant downward velocity v, which of the following describes the changes with time in the kinetic energy and gravitational potential energy of the sphere?

Kinetic Energy Gravitational Potential Energy A constant and equal to ½mv2 decreases at a rate mgv B constant and equal to ½mv2 decreases at a rate mgh C increases at a rate ½mv2 decreases at a rate (½mv2 – mgv) D increases at a rate mgv decreases at a rate (mgv – ½mv2) 10 Singapore is on the Equator. Seoul is at a latitude of 37.50 N as depicted in the diagram

below.

The centripetal acceleration at Singapore due to the Earth’s rotation about its axis is

singaporea . The centripetal acceleration at Seoul due to the Earth’s rotation about its axis is

seoula . What is the ratio singapore

seoul

a

a?

A 0.79 B 1.00 C 1.26 D 9.81

Singapore

Seoul

37.50

300 Wall


6

11 Tarzan, whose mass is 80.0 kg, needs to swing across a river filled with crocodiles in order to save Jane of mass 45.0 kg, at the middle of the river as shown in the diagram below. He has to swing from a branch, which is assumed to be fixed in position, on a vine of length 30.0 m, and initially making angle of 50o with the vertical. Tarzan swings towards Jane and grabs hold of her. Assuming that this is a completely inelastic collision, determine their common speed just after the collision.

A 9.28 m s-1 B 12.4 m s-1 C 15.6 m s-1 D 19.5 m s-1 12 A particle of mass m performs vertical circular motion as show in the diagram below.

The following two graphs show the vertical and horizontal components of the velocity of the particle along path ABC .

Calculate the centripetal acceleration at point C.

A zero B -24.91 m s C -29.81 m s D -222.1 m s

C

m

A

B

30.0 m

50o


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13 Mercury is × 105.79 10 m away from the Sun and it takes 0.241 earth years for Mercury to make one revolution around the Sun. Neptune is × 10450 10 m away from the Sun, calculate the period of its orbit around the Sun.

A 2.12 years B 18.7 years C 165 years D 330 years 14 The figure below shows the gravitational potential near the surface of the asteroid 951

Gaspra. Determine the mass of the asteroid.

A 161.00 10 kg× B 162.00 10 kg× C 163.00 10 kg× D 164.00 10 kg×

15 A 0.10 kg mass hanging from a light helical spring produces an equilibrium extension of

0.10 m. The mass is pulled vertically downwards by a distance of 0.020 m and then released. Taking g as 10 m s-2, the equation relating the displacement x of the mass from its equilibrium position and the time t after release is

A ( )0.12sin 10x t=

B 0.10cos(0.20 )x tπ=

C ( )0.020cos 0.10x t=

D ( )0.020cos 10x t=


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16 Which graph correctly shows the variation with time t of kinetic energy Ek of an object undergoing simple harmonic motion of period T?

17 A microwave source S is placed in front of a detector D, and a metal reflecting screen R is placed beyond D such that its plane is perpendicular to the line joining S to D. As the detector is moved slowly away from the source, it registers a series of maxima and minima.

It is observed that the detector moved through a distance of 5.6 cm between the first and fifth minimum. What is the frequency of the microwaves in GHz?

A 5.4 B 10.7 C 13.4 D 27.5

S D R


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18 In a two-slit interference experiment, one slit transmits twice the amplitude of the other slit. If the maximum intensity of the interference pattern is Io, the minimum intensity in the pattern would be

A zero B Io/9 C Io/4 D Io/2

19 Two sources of waves are said to be coherent if

A they are in phase. B they have a constant phase difference. C they have the same frequency and amplitude. D they can interfere constructively. 20 A single traveling light wave in vacuum is able to

A carry momentum. B create a standing wave. C propagate at any velocity. D create interference patterns. 21 Which statement about internal energy is correct?

A The internal energy of a system can be increased without transfer of energy by

heating. B The internal energy of a system is the sum of the kinetic energies of the molecules. C When the internal energy of a system is increased, its temperature always rises. D When two systems have the same internal energy, they must be at the same

temperature. 22 An ideal gas is contained in a cylinder with a movable piston. At pressure p, volume V and

temperature T, it has Nv molecules per unit volume. If the pressure of the gas is changed to 0.50p, and the temperature to 2.0T, the number of molecules per unit volume becomes

A 0.25 Nv B 0.50 Nv C 1.0 Nv D 4.0 Nv


10

23 A negatively-charged oil drop is held stationary between two horizontal, charged metal plates, the upper plate being positive. The oil-drop then acquires an additional negative charge. In order to keep the oil-drop stationary, what change should be made?

A Move the plate closer together. B Reverse the charges on the plates. C Increase the electric field strength between the plates. D Decrease the potential difference between the plates.

24 Two point charges of -5 µC and +5 µC, are situated at points P and Q respectively as

shown below. X lies midway between P and Q while Y is at the same vertical position as X but displaced to the right.

At point X At point Y

Electric field Electric potential Electric field Electric

potential A towards Q zero downwards zero B towards Q negative downwards negative C towards P zero upwards zero

D towards P negative upwards negative

+

-

Oil drop

P

Q

X Y


11

25 In the circuit diagram below, D is an ideal diode. The voltage supply has negligible internal resistance and the voltmeter reads 12 V.

If the connections to the terminals of the voltage supply are reversed, the voltmeter reading would be

A 6.0 V B 8.0 V C 9.0 V D 18 V 26 The circuit shown in Fig. 1 may be used to determine the internal resistance of a battery.

An oscilloscope is connected across the battery as shown. Fig. 2 represents the screen of the oscilloscope.

Fig. 1 Fig. 2 The time base of the oscilloscope is switched off throughout the experiment. Initially the switches S1 and S2 are both open. Under these conditions, the spot on the oscilloscope screen is at A. Switch S1 is now closed, with S2 remaining open. The spot moves to B. Switch S1 is kept closed and S2 is also closed. The spot moves to C. The vertical sensitivity of the oscilloscope is 0.50 V per division. Calculate the internal resistance of the battery.

A 0.24 Ω B 2.3 Ω C 14.0 Ω D 16.4 Ω

V

2.0 Ω

2.0 Ω

2.0 Ω

D

Voltage supply


12

27 A row of 30 decorative lights, connected in series, is connected to a mains transformer. When the supply is switched on, the lights do not work. The owner uses a voltmeter to test the circuit. When the voltmeter is connected across the fifth bulb in the row, a reading of zero is obtained. Which of the following scenarios described is not possible ?

A Only the filament of the fifth bulb has broken. B The fuse in the mains transformer has blown. C The filament of at least one of the other bulbs has broken. D There is a break in the wire from the supply to the transformer. 28 The diagram shows a network of three resistors. Two of these marked R, are identical.

The other one has a resistance of 5.0 Ω. The resistance between Y and Z is found to be 2.5 Ω. Determine the resistance between X and Y.

A 1.00 Ω B 1.9 Ω C 2.5 Ω D 4.2 Ω

R

R

5.0 Ω

X

Y

Z


13

29 In the diagram below, P is a horizontal circular coil of wire carrying a steady current 1I . A

conducting rod, which is free to move, is supported by 2 fixed horizontal parallel rails TQ and SR which are perpendicular to the length of the conducting rod and carry a constant current 2I as shown in the diagram below.

The conducting rod will

A move towards TS with increasing speed. B move towards QR with increasing speed. C move towards QR with decreasing speed. D be lifted off the horizontal parallel rails momentarily.

30 The wire AC is free to move vertically while the wire BD is fixed. Suppose that both wires

carry equal currents of 100 A in opposite directions and that the mass per unit length for each wire is 20.0 g m-1. Calculate the height which the wire AC is above wire BD. (You may assume that the magnetic field, B at a distance r from a wire carrying current I to be

o

2B

rµπ

= I)

A zero, wires AC and BD are attracted to each other. B 0.102 cm C 1.02 cm D 10.2 cm

A

B

C

D

I = 100 A

I = 100 A

R

S

Q

T

P

I1

I2

I2

I2


14

31 A short bar magnet passes at a steady speed through a long solenoid. A galvanometer is connected across the solenoid.

Which graph best represents the variation of the current I of the galvanometer with time t?

32 A copper ring is suspended by a long, light rod pivoted at X so that it may swing as a

pendulum, as shown in the diagram below. An electromagnet is mounted so that the ring passes over it as it swings. The ring is set into oscillation with switch K open. What happens to the motion after switch K has been closed?

A The periodic time will decrease. B The oscillations will be heavily damped. C The amplitude will increase because the ring is accelerated towards the magnet. D The oscillations will continue at constant amplitude while the battery can supply

energy.

G

N S

I

t

I

0

C

t

0

A

t

I

0

B

t

I

0

D

A

C

B

D I

I

I

t

t

t

t 0

0

0

0

K

X


15

33 A sinusoidal potential difference V1 as shown in Fig. A , is applied across a resistor R and produces heat at a mean rate W. What is the mean rate of heat produced when another potential difference V2 as shown in Fig. B is applied across the same resistor?

A ½W B 2W C 4W D 8W

34 An electric kettle has the following label:

Power : 2000 to 2400 W Voltage : 220 to 240V Frequency : 50 to 60 Hz

Which of the following is a probable expression of the current that passes through the kettle when used in Singapore?

A I = 8.33 sin (315t) B I = 10.9 sin (315t) C I = 14.1 sin (375t) D I = 16.0 sin (375t) 35 A potential barrier has a width W and potential height 6.0 MeV. The probability of a

3.0 MeV electron tunneling through it is 0.025. Suppose that the potential height of the barrier is now doubled, what must the width of the barrier be in order for a 3.0 MeV electron to have the same probability of transmission?

A 0.577 W B 0.707 W C 1.41 W D 1.73 W 36 The decay energy of a short-nuclear excited state is measured to be 150 keV ± 1%. What

is the shortest lifetime it can have? A 3.5 × 10-40 s B 3.5 × 10-37 s C 5.3 × 10-35 s D 2.2 × 10-19 s

V2

Fig. B Fig. A

time

Vo

-Vo

V1

0

time

2Vo

V

0 T

T


16

37 Which of the following statements about electron transitions between energy levels is true?

A Stimulated emission describes a scenario when an atom get ‘excited’ from a lower

energy state E1 to a higher energy state E2 when one of its electron absorbs a photon of energy E2 – E1.

B Spontaneous emission occurs more rapidly when the lifetime of the excited state is long.

C Stimulated emission occurs more rapidly when the stimulating photon beam is of high intensity.

D Spontaneous emission competes more strongly with stimulated emission in transitions that emit red or infrared radiation.

38 A semiconductor device is connected in a series circuit with battery and resistance. A

current is found to pass through the circuit. When polarities of the battery are reversed the current drops to zero. The device may be:

A pn junction B intrinsic semiconductor C p-type semiconductor D n-type semiconductor 39 The radioactive isotope of iodine, 123I, is often used to test for overall thyroid function in

patients. The thyroid of an individual with hypothyroid condition will accumulate less iodine than that of a normal individual. An initial dose of 123I with an activity of 30 µCi was administered intravenously to a patient. Twenty-four hours after injecting the radiopharmaceutical, the activity emanating from the thyroid region is monitored and found to be 4 µCi. What percentage of the injected 123I was concentrated in the thyroid (Half-life of 123I = 13 hrs).

A 13% B 24% C 26% D 48%


17

40 The figure below shows the apparatus used to repeat the alpha-particle scattering experiment. The detector measures the intensity of the alpha-radiation I at various angular positions θ.

Which of the graphs best represents the variation of I with θ?

A

B

C

D

End of Paper

Ι

θ 0ο

−90ο

−170

ο +90ο

+170

ο

Ι

0ο

−90ο

−170

ο +90ο

+170

ο

Ι

θ 0ο

−90ο

−170

ο +90ο

+170

ο

Ι

θ 0ο

−90ο

−170

ο +90ο

+170

ο

–90o

detector

+170o

–170o 0o

+90o

alpha particles

θ

gold foil

θ

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MJC 2010 H2 Physics Prelim Paper 1