2011 j2 h2 prelim paper 2

This question paper consists of 20 printed pages

MERIDIAN JUNIOR COLLEGE Preliminary Examination Higher 2

_______________________________________________________________________

H2 Physics 9646/2

Paper 2 15 September 2011

1 hour 45 min

_______________________________________________________________________

Class Reg Number

Candidate Name _____________________________

READ THESE INSTRUCTIONS FIRST This booklet contains 8 questions.

Do not open this booklet until you are told to do so. Answer all questions.

Write your answers on this question booklet in the blanks provided.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question. Marks will be deducted if units are not stated where necessary or if answers are not quoted to the appropriate number of significant figures. All working for numerical answers must be shown. You are reminded of the need for good English and clear presentation of your answers.

Examiner’s Use

Section A

Q1 /5

Q2 /5

Q3 /12

Q4 /10

Q5 /6

Q6 /14

Q7 /8

Section B

Q8 /12

Deductions

Total /72

Preliminary Examination Meridian Junior College 15 September 2011 JC2 H2 Physics 2011

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 Cthe Planck constant h = 6.63 x 10-34 J sunified atomic mass constant u = 1.66 x 10-27 kgrest mass of electron me = 9.11 x 10-31 kg

rest mass of proton mp = 1.67 x 10-27 kgmolar 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 + 12

at2

v2 = u2 + 2as work done on/by a gas W = pΔV 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 2

o -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

= 12

0.693t


3

Answer all the questions in the spaces provided.

1 A stone is projected with in initial speed of 30.0 m s-1 at an angle of 30.00 from an inclined plane as shown in Fig. 1.1 below.

Fig. 1.1

(a) Show that the expressions for the displacements of the stone perpendicular and parallel to the inclined plane is respectively given by:

2

2

15.0 - 4.61

26.0 1.68 y

x

s t t

s t t

=

= + [2]

(b) Determine the distance along the inclined plane where the stone will land.

Distance = ………………….. m

[3]

30.0°

30.0 m s-1

stone

20.0o


4

2 (a) Explain why an object submerged in a fluid experiences upthrust.

............................................................................................................................................

............................................................................................................................................

.................................................................................................................................. [2]

(b) A styrofoam board of thickness 10 cm, cross sectional area 0.857 m2 and density 300 kg m-3 is floating in a swimming pool. On top of the float sits a child as shown in Fig. 2.1 below.

Fig. 2.1

Suppose the child were to be replaced by his father of mass 75 kg instead, determine the acceleration of the board at the instant it starts to sink from the position shown in Fig. 2.1. Ignore any drag force. Density of swimming pool water is 1000 kg m-3.

Acceleration = ………………….. m s-2 [3]

styrofoam board water level


5

3 (a) (i) A wave is travelling on a string in the x-direction. Fig. 3.1(a) and Fig. 3.1(b) show the variation with distance x of the displacement y of the string: Fig. 3.1(a) corresponds to time t = 0 s while Fig. 3.1(b) corresponds to time t = 0.2 s

Use Fig. 3.1(a) and Fig 3.1 (b) to determine, for this wave, 1. its wavelength. Wavelength = ………………………. m [1] 2. its speed.

Speed = ………...…………. m s-1 [2]

3. its period.

Period = ………………………. s [2]

Fig. 3.1 (a) (t = 0 s)

Fig. 3.1(b) (t = 0.2 s)


6

(ii) The speed v of a travelling wave is given by the expression:

v fλ=

It tells how fast the wave-fronts are moving forward. On the other hand, a stationary wave does not have a speed. By reference to the formation of a stationary wave, explain the significance of the product fλ for a stationary wave.

……………………………………………………………………………………………….

……………………………………………………………………………………………….

……………………………………………………………………………………………….

……………………………………………………………………………………… [2]

(b) Fig. 3.2 shows a swinging pendulum.

Fig 3.2 At position A, the pendulum bob is momentarily at rest and the string of the pendulum makes an angle θ with respect to the vertical. At position B, the pendulum bob is at its lowest position and its velocity is v. The length of the string is L and the diameter of the bob is d (d << L). The mass of the bob is m.


7

(i) By considering the principle of conservation of energy, express v in terms of g, L and cosθ.

[2]

(ii) Using a free body diagram or otherwise, deduce an expression for the acceleration of the bob at A. [1]

(iii) Also, deduce an expression for the acceleration of the bob at B. [1]

(iv) Hence, determine the acceleration of the bob at B when the angle θ is small.

Acceleration =………...…………. m s-2 [1]


8

4 The apparatus shown in Fig. 4.1 is setup to study the photoelectric effect.

Fig. 4.1

(a) When a source of violet light of frequency 7.4 x 1014 Hz illuminates the caesium surface, the ammeter reading is just reduced to zero by applying a potential difference of 1.19 V between the electrodes. Determine the work function of caesium in joules.

Work function = ……………………. J [3] (b) Hence, determine the maximum kinetic energy of electrons emitted from the caesium

surface when it is illuminated by blue light of frequency 6.4 x 1014 Hz.

Maximum kinetic energy = ……………………. J [1]

micro-ammeter

variable d.c. supply

illuminated caesium surface

vacuum


9

(c) Fig. 4.2 shows the variation of the photocurrent with the potential difference applied

between the electrodes when violet light illuminates the caesium surface.

Fig. 4.2

On Fig 4.2, sketch how the graph will change if a lower intensity of violet light is used. Explain your answer.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

..................................................................................................................................

[3]

(d) Two students argue about the effect of shining both the blue and the violet light on to the

caesium at the same time. Andy claims that the maximum kinetic energy of the emitted electrons is the sum of the kinetic energies for the individual colours; Ben claims that it is the mean of the values for the individual colours. Comment on the validity of their statements.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

..................................................................................................................................

[3]

I / μA

V / VVS


10

5 (a) Explain why the upper lasing level of a laser should be a metastable state.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

.................................................................................................................................. [2]

(b) By reference to the band theory of conduction, explain why the electrical resistance of an intrinsic semiconductor material decreases as its temperature rises. You may draw a labelled diagram if you wish.

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

............................................................................................................................................

..................................................................................................................................

[4]


11

6 On 11 March 2011, Japan suffered a Magnitude 9.0

Earthquake off the eastern coast of Japan. One of the consequences of the Earthquake was a tsunami that crippled the Fukushimi Daiichi nuclear power plant, which subsequently released significant amounts of radioactive material into the atmosphere and environment. The table shows the activities of several radionuclides measured on 31 March 2011 from soil samples at several locations in and around the Fukushima district.

(source: http://www.acro.eu.org/RAP110411‐OCJ‐EN.pdf)

Table 6.2 Radionuclide Half-life Decay

mode Tellurium-129m 33.6 days Gamma Tellurium-132 3.20 days β- Iodine-132 2.30

hours β-

Iodine-131 8.02 days β- Cesium-134 755 days β- Cesium-137 30.1

years β-

Barium-140 12.8 days β- Lanthanum-140 1.68 days β-

Fig 6.1 Snapshot of the elements around iodine from the periodic table.

Table 6.1 Surface activity (Bq /m2) Location Tellurium-

129m Tellurium-132 / Iodine-132

Iodine-131 Cesium-134

Cesium-137

Barium-140 / Lanthanum-140

A 208,370 111,960 824,150 205,260 211,480 8,397 B 388,600 195,640 1,163,120 477,040 479,720 22,244 C 754,920 382,120 1,887,300 894,720 922,680 35,416 D 71,928 35,478 481,140 77,031 78,489 2,527

Atomic number Chemical symbol

Chemical name Relative Atomic mass


12

(a) Using the data from Table 6.1, Table 6.2 and Fig 6.1,

(i) Write down the decay equation for: [2]

1. Iodine-131

2. Tellurium-129m

(ii) Calculate Aβ, the total activity per m2 due to beta decay only of the most contaminated region, based on the data provided.

Aβ = …………………. Bq [1] (iii) For the region identified in (a)(ii), calculate: 1. N, the number of iodine-131 nuclei present per m2.

N = ……………………. [2] 2. Calculate Ai, the total activity present due to iodine-131 in 7.5 km2 of the region.

Ai ………………….. Bq [2] (b) Explain why after 16.1 days, another sample taken at the same location had significantly

more than 41 of the original activity (per m2) due to iodine-131.

....................................................................................................................................................

....................................................................................................................................................

....................................................................................................................................................

.........................................................................................................................................

[2]


13

(c) Among the radioactive fallout, iodine-131 and cesium-137 are major concerns as both elements can be absorbed by the human body through inhalation as well as through the consumption of contaminated food and water.

(i) Even though the activity of iodine-131 is significantly greater than that of cesium-137 in all locations tested, cesium-137 will present a greater hazard in the long term. Explain why.

....................................................................................................................................................

....................................................................................................................................................

....................................................................................................................................................

.........................................................................................................................................

[2]

(ii) Iodine is absorbed by the body and accumulates in the thyroid. Explain why iodine-131 is dangerous when ingested.

....................................................................................................................................................

....................................................................................................................................................

....................................................................................................................................................

.........................................................................................................................................

[2]

(iii) Explain why the consumption of Potassium Iodide pills salt may help reduce the chances damage to the thyroid or contracting thyroid cancer.

....................................................................................................................................................

....................................................................................................................................................

.........................................................................................................................................

[1]


14

7 (a) An AC generator consists of a coil of 100 turns with an area of 120 cm². The generator

produces a peak voltage of 29 V when the coil is turning at 6000 revolutions per minute in a uniform magnetic field.

(i) Show that the general formula for e.m.f. generated by the coil is ε=NBAωsin(ωt),

where N is the number of turns, A is the area of the coil and B is the magnetic flux density. [1]

(ii) Hence, determine B, the magnetic flux density that the coil is experiencing.

B = ………………….. T [2] (ii) The rate of rotation is reduced to 3600 revolutions per minute. Calculate the new

peak output voltage.

Peak output voltage = ……………………. V [2]


15

(b) The coil is replaced with a new wire. This wire is bent into the shape of a semicircle of

radius 0.20 m. A uniform magnetic field which has a flux density of 0.80 T acts normally to the plane of the semicircular wire. As the wire is rotated at a constant rate, it generates an alternating e.m.f with a peak-to-peak value of 0.31 V Calculate the angular speed at which the wire is rotated.

Angular speed = ………………………….. rad s-1 [3]


16

Section B

It is recommended that you spend about 30 minutes on this question

8 Double glazed windows consist of two panes of glass separated by an air to reduce heat transfer across. Double glazing can also be used for sound insulation. Fig 8.1: Window Fig 8.2: Laboratory Model of double glazed window. Manufacturers reduce the air pressure in the space between the panes of glass to reduce the sound transmitted through the window. It is suggested that the amplitude of sound transmitted through a double-glazed window is related to air pressure in the space between the panes. Fig 8.2 shows a laboratory model of a double glazed window. It consists of two panes of glass connected together. A tube is connected to the space between the panes so that air may be removed. Design a laboratory experiment to investigate how the strength of sound varies as pressure between the glass panes varies. You may assume that the following equipment is available, together with any other apparatus that may be found in a school or college science laboratory. Laboratory model of double glazed window, signal generator, speaker, pressure gauge, microphone, cathode ray oscilloscope, pump, d.c. power supply, connecting wires, insulating materials. You should draw a diagram showing the arrangement of your apparatus. In your account you should pay particular attention to (a) the equipment used for investigation,

(b) the procedure to be followed,

(c) the control of variables,

(d) any safety precautions,

(e) any precautions you would take to improve the accuracy of the experiment.


17

Class Reg Number

Candidate Name _____________________________ Diagram: Please make use of this page and next two pages to write your answers to Q8:

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................


18

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................


19

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

................................................................................................................................................

End of Paper


20

Answers 1(b) 102 m 2(b) 1.5 m s-2 3(a)(i)1. 0.080 m 2. 0.16 m s-1 3. 0.5 s (b)(i) v = θ−2 (1 cos )gL (ii) a = gsinθ (iii) a = v2 /L or a = 2g(1-cosθ) (iv) a = 0 4(a) 3.0 × 10-19 J (b) 1.24 × 10-19 J 6(a)(ii) 4.1222 × 106 Bq (iii)1. 1.89 × 1012 2. 1.42 × 1013 Bq 7(a)(ii) 0.0385 T (iii) 17.4 V (b) 3.08 rad s-1

2011 j2 h2 prelim paper 2

Documents