2010H2MI_Physics Prelim

8/12/2019 2010H2MI_Physics Prelim

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Data

speed of light in free space, c = 3.00 10 8 m s 1

permeability of free space, 0 = 4 10 7 H m 1

permittivity of free space, 0 = 8.85 10 12 F m 1

= (1/(36 )) 10 9 F m 1

elementary charge, e = 1.60 10 19 C

the Planck constant, h = 6.63 10 34 J s

unified atomic mass constant, u = 1.66 10 27

kg

rest mass of electron, m e = 9.11 10 31 kg

rest mass of proton, m p = 1.67 10 27 kg

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

the Avogadro constant, N A = 6.02 10 23 mol 1

the Boltzmann constant, k = 1.38 10 23 J K 1

gravitational constant, G = 6.67 10 11 N m 2 kg 2

acceleration of free fall, g = 9.81 m s 2

www.erwintuition.com



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Formulae

uniformly accelerated motion, s = ut +21 at 2

v 2 = u 2 + 2as

work done on/by a gas, W = p V

hydrostatic pressure, p = g h

gravitational potential, =

r Gm

displacement of particle in s.h.m. x = x o sin t

velocity of particle in s.h.m., v = v o cos t

v = x o 2 x 2

mean kinetic energy of a molecule ofan ideal gas E =

resistors in series, R = R 1 + R 2 +

resistors in parallel,R 1 = ...11

21

++R R

electric potential,V = r

Q

04

alternating current/voltage, x = x o sin t

transmission coefficient T = exp( 2kd )

where k =2

2 )(8h

E U m

radioactive decay, x = x 0 exp( t )

decay constant, =21

6930t

.




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1. In the equation, P = Q RS , P , Q , R and S are physical quantities. For theequation to be homogeneous, which of the following must be true.

A. P , Q , R and S all have the same units.

B. P , Q , R and S are all scalar quantities.

C. The product RS have the same units as P and Q .

D. The product RS is numerically equal to ( Q P )

2. A student wishes to determine the density of a cylinder of mass M , height

h and diameter of cross section d , using the formula M = d 2

4h . If the

percentage uncertainties of his measurements of M , d and h are 3%, 1%and 2% respectively, what will be the percentage uncertainty of ?

A. 3% B. 5%

C. 6% D. 7%

3. A train travelling at 2.0 m s -1 passes through a station. The graph belowshows the variation with time, t of the speed, v of the train after leaving thestation.

What is the speed of the train when it is 150 m from the station?

A. 6.0 m s -1 B. 8.0 m s -1

C. 10 m s -1 D. 12 m s -1




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4. Which of the following is a false statement regarding how two forces giverise to a couple?

A. They act in opposite directions.

B. They both act at the same point.

C. They both act on the same body.

D. They both have the same magnitude.

5. A string of negligible mass with a weight of 50 N at one end is attached atthe other end to a fixed point P . The sphere is acted upon by a horizontalforce of 80 N such that the string makes an angle to the vertical. What isthe value of ?

A. B.

C. D.

6. Five blocks of equal masses V, W, X, Y and Z are connected by four

identical strings as shown in the diagram below. They are pulled by asteadily increasing force F . Which of the strings A, B , C or D is most likelyto break first?

`




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7. A 60 kg archer stands at rest on frictionless ice and fires a 0.50 kg arrowhorizontally at 50 m s -1. What is the final velocity of the archer as he movesacross the ice after firing the arrow?

A. 0.42 m s-1

B. 0.48 m s-1

C. 0.60 m s -1 D. 0.72 m s -1

8. A stone of weight 80 N is thrown vertically upwards from the ground with aninitial kinetic energy of 150 J. Ignoring air resistance, the kinetic energy, thegain in potential energy, and the work done against gravity when the stone

is at 1.00 m above the ground will be Kinetic Energy Gain in Potential

Energy

Work Done

A. 70 J 70 J 70 J

B. 70 J 80 J 70 J

C. 70 J 80 J 80 J

D. 80 J 150 J 80 J

9. A block of iron is suspended in water

The block experiences an upthrust from the water.

Which is the explanation for this upthrust?

A. Iron is more dense than water.

B. The area of face R is greater than the area of face S .




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C. The density of water increases with depth.

D. The pressure of water increases with depth.

10. A helicopter which has blades of diameter 5.0 m is hovering above theground at a particular instance. Its blades are rotating in such a way that

they are pushing air downwards at a speed of 18 m s-1

.

The density of the surrounding air can be taken as 1.02 kg m -3.

The upward force acting on the blades is

A. 360 N B. 1400 N

C. 6500 N D. 26000 N

11. To travel at constant speed, a car engine provided 25 kW of useful power.The driving force on the car is 600 N. At what speed is the car travelling at?

A. 2.5 m s -1 B. 4.0 m s -1

C. 25 m s-1

D. 42 m s-1

12. A satellite is in circular orbit 144 km above the Earth. Assuming that theradius of the Earth is 5760 km, the gravitational force on the satellitecompared with that when it is at the Earths surface is approximately

A. greater by 10%

B. greater by 5%

C. the same

D. less by 5%




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13. Why does the Moon stay in its orbit at a constant distance from the Earth?

A. The gravitational pull of the Earth on the Moon is just sufficient to cause

the centripetal acceleration of the Moon.

B. The gravitational pull of the Earth on the Moon balances the

gravitational pull of the Moon on the Earth.

C. The gravitational pull of the Moon on the Earth is negligible at this

distance. D. The centripetal force the Earth exerts on the Moon balances the

centripetal force the Moon exerts on the Earth.

14. P is a planet with centre O, as shown in the figure below. X and M are twopoints of equal gravitational potential, A . Y and N are two other points of

equal gravitational potential, B .

Which of the following statements is correct?

A. The work done by an external agent to move a mass from Y to X is

negative.

B. The work done by the gravitational field to move a mass from X to N is




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by heating.

B. The internal energy of a system is dependent only on its temperature.

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.

18. A heater of power of 300 W is immersed in a filter funnel of crushed ice.Before the heater is switched on, 10 g of water is collected from the meltingice in 1 minute. When the heater is switched on, the mass of water collectedfrom the melting ice in 1 minute is 85 g. The specific latent heat of fusion ofice, in J g -1 is

A. 5 B. 240

C. 300 D. 1200

19. A star emits electromagnetic waves of wavelengths 50 m, 5 m, 0.5 m and0.05 m. In which regions of the electromagnetic spectrum are they?

Wavelength

50 m 5 m 0.5 m 0.05 m

A. infra-red infra-red visible ultraviolet

B. infra-red visible ultraviolet x-ray

C. microwave visible visible ultraviolet

D. radio infra-red visible ultraviolet

20. A stationary sound wave has a series of nodes. The distance between thefirst and the sixth antinode is 30.0 cm.

What is the wavelength of the sound wave?

A. 5.0 cm B. 6.0 cm




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C. 10.0 cm D. 12.0 cm

21. Monochromatic light with a wavelength of is incident normally on adiffraction grating. The angle between the directions of the two second-orderdiffracted beams is .

What is the spacing of the lines on the grating?

A. 2 sin

B.

sin

C. 2

sin 2( )

D.

sin 2( )

22. A sphere is released from rest, in vacuum, between two parallel, verticalmetal plates with a separation of 0.10 m. The sphere has a weight of

1.6 10 3 N and an electric charge of +2.0 C. The potential differencebetween the two plates is 80 V.

Which of the following depicts the path of the sphere after release?




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23. A positive charge is placed at P and a negative charge is placed at Q. Theelectric potential at different points between these two charges is shown inthe figure below.

Which of the following graphs correctly shows the variation with distance, x along line PQ of the electric field strength, E ?

A. B.




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C. D.

24. Two charges, P and Q are 100 mm apart.

X is a point on the line between P and Q. If the potential at X is 0 V, what isthe distance from P to X?

A. 40 mm B. 45 mm

C. 50 mm D. 60 mm

25. What is the definition of resistance?

A. Resistance is the potential difference per unit current.

B. Resistance is the gradient of the graph of potential difference against

current.

C. Resistance is the voltage required for a current of 1 A.

D. Resistance is defined by the equation R =

l A

, where is the resistivity

of the material, l is the length of the wire, and A is its cross-sectional

area.

26. A main circuit has six identical bulb connected in series. One of the bulbshas a broken filament. Voltmeters X and Y of infinite resistance are placed inthe circuit as shown.




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What are the voltmeter readings?

X reading Y reading

A. 0 V 0 V

B. 0 V 240 V

C. 40 V 40 V

D. 240 V 0 V

27. A diode is connected to a battery as shown below.

Which of the following statements about the diode is not true?

A. No current flows through the diode.

B. The resistance is very large.

C. The voltage across the diode is zero.

D. The voltage across the diode is the same as the e.m.f. of the source.




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Which of the following graph shows how the magnitude of the magnetic forceF on the wire varies with in the range 0 to 90?

A. B.

C. D.

30. Two long straight wires, X and Y are placed perpendicular to each other at asmall distance, d apart, with wire X vertically above the point R. The currentin wire X is out of the page and the current in wire Y is to the right as shownin the figure below.

What is the direction of the force acting on wire Y at point P due to the




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magnetic field produced by wire X?

A. Out of the page

B. Into the page

C. Upwards D. Downwards

31. An e.m.f. is induced in a wire that is subjected to a varying magnetic field.The following graphs show how magnetic flux density, B of this field varieswith time, t .

At what time is the magnitude of the e.m.f induced in the wire at itsmaximum?

A. 1 ms B. 2 ms

C. 3 ms D. 4 ms

32. Two flat horizontal coils are mounted as shown




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Which of the following actions will cause the galvanometer to register acurrent?

1. With switch S closed, Coil 2 is stationary while Coil 1 is movedupwards.

2. Both coils are stationary and S is switched on and off. 3. With switch S closed, the variable resistor R is increased and

decreased rapidly.

A. 2 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2 and 3

33. A sinusoidal alternating current flows through a resistor.

What is the mean power dissipated in the resistor?

A. 12

maximum current( )2

B. 12

maximum power( )

C. 12

maximum current( )2

D. 12

maximum power( )




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34. The half-wave rectification of an alternating current sinusoidal voltage ofamplitude 100 V gives the waveform as shown in the figure below. The r.m.s.value of the rectified voltage is

A. 25 V B. 50 V

C. 71 V D. 100 V

35. A laser beam of power, P has wavelength, . What is the rate of photonsproduced?

A. hc P

B. Ph

c

C. Phc D. P hc

36. Which of the following observations regarding the photoelectric effect is not predictedby the classical theory of electromagnetic radiation?

A. The rate of photoelectric emission is proportional to the intensity of the incidentradiation.

B. Irrespective of the intensity of radiation, photoelectric emission is instantaneous.

C. Photoelectric emission is observable using any part of the electromagnetic

spectrum.

D. The maximum kinetic energy of the photoelectrons is dependent on the intensity

of the radiation.




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37. At room temperature, the charge carriers inside a p-type semi-conductor are

A. holes only

B. electrons only

C. positive ions

D. both holes and electrons

38. The following diagram illustrates the upper energy bands in two different classes ofsolids at absolute zero. The shaded areas represent occupied electron energy levels.

What are bands P and Q, and classes X and Y of solids?

Band P Band Q Class X Class Y

A. conduction valence intrinsic semi-conductor metal B. conduction valence metal intrinsic semi-conductor

C. valence conduction intrinsic semi-conductor metal

D. valence conduction metal intrinsic semi-conductor

39. Which of the following equations correctly shows an -particle causing a nuclearreaction?

A. 7

14 N + 24 He 8

17 O + 11n

B. 8

17 O + 24 He 9

20 F + 11p

C. 8

17 O + 10 e 5

13 B + 24 He

D. 7

14 N + 11p 6

11 C + 24 He




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40. Initially, a source comprises N o nuclei of a radioactive nuclide. What is the number of nucleidecayed after a time interval of three half-lives?

A. N o 16

B. N o

8

C. 7N o 8

D. 15 N o

16

END OF PAPER




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Class Adm No

Candidate Name:

This question paper consists of 23 printed pages and a blank page.

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Preliminary Examination II 2010Pre-university 3

H2 Physics 9646

Paper 2 Structured Questions 9646/02

Friday 17 September 1h 45m

Candidates answer on the Question Paper.

No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

For Examiners Use

1

2

3

4

5

6

7

8

Write your name, class and admission number in the spaces at the

top of this page.Write in dark blue or black pen.You may use a soft pencil for any diagrams, graphs or roughworking.Do not use staples, paper clips, highlighters, and glue or correctionfluid.

Section AAnswer all questions.It is recommended that you spend about 1 hour 15 minutes on thissection.

Section BAnswer Question 8It is recommended that you spend about 30 minutes on this section

At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of eachquestion or part question.

Total




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Data




= (1/(36 )) 10 9 F m 1



unified atomic mass constant, u = 1.66 10 27 kg











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Formulae


v 2 = u 2 + 2as




r Gm



v = )( 22 x x o


32

kT



21

++R R

electric potential,V =

r Q

04



where k =2

2 )(8h

E U m


decay constant, =21

6930t

.




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Section A

Answer all questionsIt is recommended that you spend about 1 hour 15 minutes on this section.

1. (a) Distinguish between a scalar quantity and a vector quantity, providing an example foreach.

....[2]

(b) A ship is initially cruising in the direction bearing of 045 at a speed of 10 m s -1 changes direction to head in a new direction bearing of 145 at a speed of 5 m s -1, asseen in Fig. 1.1 . The manoeuvre was completed in 30 s.

Fig. 1.1

Using a vector diagram or otherwise, calculate the acceleration of the ship during thechange in direction.

acceleration of the ship =..m s -2 at bearing of [3]




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(iii) Assuming that it is a perfect shot (i.e. the rifle was perfectly horizontal and wasaimed properly at the head of the target), calculate the vertical distancebetween his aiming point and where the bullet actually hits the target.

vertical distance =m [2]

(iv) After passing through the target, the bullet is entrenched 4.0 m deep into asandbag that is directly behind the target board.

Calculate the average deceleration of the bullet as it moves within the sandbag

average deceleration =.m s -2 [2]

(v) If the assumption was not made in (b) (ii) , state whether the bullet would hit thetarget at a lower or higher point than what was calculated in (b) (iii).

...[1]

3. (a) Using the simple Kinetic Model of Matter, explain the following:

(i) the melting of ice takes place without a change in temperature.

...[2]

(ii) the specific latent heat of vaporisation of water is higher than its specific latentheat of fusion.

...[2]




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(b) An ideal gas at constant pressure has its volume directly proportional to its absolutetemperature.

Calculate the absolute temperature T when an ideal gas has volume 0.00825 m 3,assuming that the same mass of the ideal gas at the same pressure has volume0.00424 m 3 at a temperature of 273 K.

absolute temperature T =.K [2]

(c) (i) State the conversion formula from the Celsius scale (C) to the thermodynamicabsolute scale (K)

[1]

(ii) Hence or otherwise, comment on whether the following statement is true:

Today the temperature is 30 C and yesterday it was 15 C. Hence it is twiceas hot today as it was yesterday.

...[1]




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4. (a) A 1 kg solid block of iron, when placed on water, will sink. The same block of iron isshaped into a model of a boat, and this model would float on water.

Explain why the boat model would float, and not sink.

.......[2]

(b) A string supports a solid iron object of mass 200 g. The solid iron object is hencesuspended in mid-air

(i) Calculate the tension in the string when the solid iron object is suspended bythe string in mid-air

tension in the string =. N [1]

(ii) Given that the density of iron is 8000 kg m -3, calculate the volume of the solidiron object

Volume of solid iron object =.. m3

[1](iii) Calculate the new tension in the string when the solid iron object is completely

immersed in a liquid of density 800 kg m -3.

New tension in string = N [2]




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(c) A solid cube with sides of length, x is placed on the surface of a fluid. The cube isthen slowly pushed downwards into the fluid, as seen in Fig.. The distance from thebase of the cube to the surface of liquid is given by h . The cube is pusheddownwards until h >> x.

Fig. 4.1

Fig. 4.2

Sketch in, Fig. 4.2 above, the graph showing the variation of the upthrust acting oncube due to the fluid against the distance from the base of the cube to the fluidsurface, h . Your graph should show the variation of upthrust for values of h that aregreater than x .

[2]




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5. (a) Define magnetic flux density .

....[2]

(b) Fig. 5.2 below shows a loosely-coiled metal spring hanging from a fixed point.

Fig. 5.1

The ends of the spring are connected to a circuit as shown in Fig. 5.1. When acurrent is switched on, the spring becomes compressed (i.e. the coils move closer toone another and the vertical length of the spring becomes slightly shorter thanbefore).

(i) Explain why the spring shortens in length when the current is switched on.

...[2]




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(ii) State and explain the changes (if any) in the kinetic energy of electron due tothe magnetic force acting on it.

...[1]

6. (a) State and explain briefly the conditions necessary for the production of a laser beam.

....

....

....

....

....

........[3]




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ForExaminersUse

(b) Complete the table below to show the three differences between light from a filamentlamp and laser light .

Light from a filament lamp Laser light

[3]




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7. X-rays are emitted when a metal target is bombarded by high-energy electrons. The X-rayspectrum consists of a broad continuous spectrum and a series of sharp lines known asthe line or characteristic X-ray spectrum.

The K-series line spectrum arises when an incoming electron removed an atomic electronfrom the innermost shell, K-shell ( n = 1). An electron from the L-shell ( n = 2) may fill thevacancy, and in the process emits a photon. The photon emitted has an energy thatcorresponds to the wavelength of the K -line shown in Fig. 7.1 .

Fig. 7.1

(a) (i) Explain how the continuous spectrum is formed.

...[2]

(ii) Explain why there is a minimum wavelength 0 for the continuous spectrum.

...[1]




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(iii) Explain how the K -line arises.

...[1]

(b) In 1913, a British physicist H. G. J. Moseley measured the wavelength of thecharacteristics X-rays from a number of elements. He noted that when the square-root of the frequency f is plotted against the position Z (atomic number) of theelement in the periodic table, a straight line results.

The energy for a multi-electron atom is given by the expression

( )2

21n

Z k E n

=

where k is a constant

(i) Show that the frequency f of the K -line is given by the expression

( )1= Z C f

where C is a constant.[2]




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(ii) The experimental data for the variation with of f are shown in Fig. 7.2 .

On Fig. 7.2 , draw the best-fit line for the points.[1]

Fig. 7.2




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(iii) Determine the constant C , with its unit.

C =

unit =[2]

(iv) Hence, or otherwise, determine the wavelength of the K -line for copperwhose atomic number Z is 29.

wavelength =.. m [2]

(c) The X-ray spectrum can be studied using the X-ray diffraction. A particular set ofcrystal planes that have a known spacing d is chosen, as seen in Fig. 7.3 Theseplanes effectively reflect different wavelengths at different angles.

Fig. 7.3




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(i) Fig. 7.4 shows a graph of intensity against angular position (measured indegrees) for the diffraction of an X-ray beam by a crystal. The beam consists oftwo wavelengths, and the spacing d between the reflecting planes is 0.94 nm.

Fig. 7.4

The condition for constructive interference is given by the expression m d =sin2 , which is known as Braggs law.

Using Braggs law, calculate the values of these two wavelengths of the X-raybeam.

1 = pm [1]

2 = pm [1]




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(ii) A standard optical diffraction grating where the grating spacing is 3000 nmcannot be used to discriminate between different wavelengths in the X-rayregion of approximately 0.1 nm.

Using the formula for the calculation of the diffraction angle, given thewavelength and grating spacing, explain quantitatively why this is so.

...[2]




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Section B

Answer Question 8It is recommended that you spend about 30 minutes on this section.

8. A manufacturer of filament lamps for use as a night-light in children's bedrooms is concernedabout the surface temperature of the glass envelope after the lamp has been left on for sometime, The surface temperature must not be too high, otherwise there is a danger of burns or fireresulting from accidental contact with the surface of the lamp. However, it is important that thepower output from the lamp should not be too small, otherwise the lamp will be too dim to beuseful.

Power supplyConnecting wiresLight bulbs of different diameters

3 V batteryCrocodile clipsSignal generatorMicrophoneBunsen burnerLoudspeaker

VoltmeterAmmeterOscilloscope

Bucket of waterThermometerRheostatThermistorThermocouple

Your answer should contain a diagram showing how the chosen equipment would bearranged, together with details of

(a) the procedure to be followed,

(b) your choice of the type of thermometer used to measure the surface temperature of thelamp,

(c) how the electrical power would be measured,

(d) any relevant safety precautions you may take when carrying out the experiment,

(e) any particular features of your design that may improve the accuracy of your experiment.

[12]




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ForExaminersUse

DIAGRAM




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END OF PAPER




45/77

Class Adm No

Candidate Name:

This question paper consists of 33 printed pages and a blank page

[Turn over

Preliminary Examination II 2010Pre-university 3

H2 Physics 9646

Paper 3 Longer Structured Questions 9646/03

Monday 20 September 2h

Candidates answer on the Question Paper.

No Additional Materials are required.

READ THESE INSTRUCTIONS FIRST

For Examiners Use

1

2

3

4

5 6

7

Total

Write your name, class and admission number in the spaces at the

top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or roughworking. Do not use staples, paper clips, highlighters, and glue or correctionfluid.

Section AAnswer all questions.

Section BAnswer any two questions.

You are advised to spend about one hour on each section.At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of eachquestion or part question.




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Data




= (1/(36 )) 10 9 F m 1



unified atomic mass constant, u = 1.66 10 27 kg











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[Turn Over

ForExaminersUse

Formulae


v 2 = u 2 + 2as




r Gm



v = )( 22 x x o


32

kT



21

++R R

electric potential,V = r

Q

04



where k =2

2 )(8h

E U m


decay constant, =21

6930t

.




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ForExaminersUse

(a) Calculate the initial reading of the weight sensor when the elevator is stationary.

initial reading of weight sensor =..N [1]

(b) The lift accelerates upwards with an acceleration of 2.5 m s -2.

(i) Draw a free-body diagram of the man, indicating and labelling the forces actingon him.

There is no need to show the magnitude of the forces involved. [1]




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(ii) Hence or otherwise, calculate the reading of the weight sensor when theelevator is accelerating upwards at 2.5 m s -2.

Reading of weight sensor =.N [2]

(iii) If the maximum G-force that can be experienced safely by a human is 1.5G

(i.e. 1.5 times of the humans weight), calculate the maximum upwardacceleration of the elevator that is still considered safe.

Maximum safe upward acceleration =. m s -2 [1]

(c) A computer simulation is designed to test the response of the emergency brakingmechanism and the weight sensor should the elevators cable snap when there arepassengers onboard. The simulation takes place in the following sequence:

Time / s Incident 0 Elevator is stationary at a height of 250 m. t1 Steel cable snaps and elevator starts to

freefall. t2 Emergency braking system kicks in andelevator undergoes deceleration.

t3 Elevator comes to a complete stop.




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Sketch a graph using the axes provided in Fig. 1.2 below to show the variation of theweight sensors reading with time during the simulation. The original reading, W , isindicated.

[2]

Fig. 1.2

(d) The owner of the skyscraper decided to replace the motor powering the elevator as itwas not efficient enough. He decided to use a motor that is 75% efficient, replacing

the original model which is 60% efficient.




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(i) If the elevator is designed to hold up to 8000 N of passenger weight, and isrequired to rise up to a height of 250 m in 60 s, calculate the power required toachieve the task.

power required = W [2]

(ii) Hence, calculate the input power that is required to operate the new motor.

input power =.W [1]




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2. (a) State the formula to calculate the centripetal force required to keep a body of massm , moving in a circle of radius r with speed v .

....[1]

(b) A smooth toy car track is set up in the following manner as seen in Fig. 2.1 below.

Fig. 2.1

Cars 1 and 2 are identical in construction and have a mass of 500 g each. Car 1 isreleased from rest at point A, which is at a height of 0.60 m. Car 1 is designed tomove down the slope and complete the circular loop (during which it would be upsidedown at the top of the loop), before colliding with Car 2 .

(i) Calculate the speed of Car 1 at point B after it has moved down the slope.

speed of Car 1 at point B =.. m s -1 [2]




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(ii) If Car 1 was to just reach point C, i.e., it comes to a complete stop at point C,state the height of the circular loop.

height of circular loop = m [1]

(iii) Explain why if the circular loop has the height that is calculated in (b) (ii), Car 1would be unable to complete the entire loop safely.

..

..

..... [2]

(iv) Hence or otherwise, calculate the maximum radius of the circular loop.

maximum radius of circular loop =m [2]




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(c) After completing the loop, Car 1 collides elastically with Car 2 . Car 1 comes to acomplete stop, and Car 2 moves forward and compresses the spring until it comes toa complete stop

Given that the spring constant of the spring is 150 N m -1, calculate the compressionof the spring when Car 2 comes to a complete stop.

compression of spring = m [2]




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3. (a) In Fig. 3.1 below, the battery has an internal resistance r and the ammeter hasnegligible resistance.

Fig. 3.1

The graph in Fig. 3.2 below shows how current I in the circuit varies as the potentialdifference V across the variable resistor R changes.

Fig. 3.2




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(i) Define the term potential difference.

...[2]

(ii) 1. Show that the e.m.f E of the battery is 6 V. [2]




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2. What is the power dissipated in the variable resistor R when the currentin the circuit is 1.2 A?

power dissipated =..W [2]

3. What is the internal resistance r of the cell?

internal resistance r = [2]




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(b) Four resistors are connected as shown in Fig. 3.3 below. Point a is at a higherpotential than point b .

Fig. 3.3

If a wire is connected from c to d, state and explain the direction of the current thatwill flow through the wire.

[2]




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4. Fig. 4.1 below shows an arrangement used to determine the wavelength ofmonochromatic light emitted by a laser.

Fig. 4.1

S1 and S2 are slits that are at right angles to the plane of this page. When illuminated bylight from the laser, they form coherent sources of light. An interference pattern is formed

on the screen, from which measurements can be taken to determine .

(a) Explain what is meant by interference of two coherent sources.

[2]




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(b) (i) Describe briefly the interference pattern produced using the arrangementshown in Fig. 4.1 above.

...[2]

(ii) Describe the roles played by diffraction and interference in the production ofthe interference pattern.

...[2]

(iii) Calculate the wavelength of light emitted by the laser, given the followingvalues:

D = 2.0 m a = 0.5 mm Fringe spacing = 2.5 mm.

wavelength = nm [2]




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(c) The interference pattern is easier to observe when the amplitudes of the waves fromthe two coherent sources are similar.

Explain why this is so.

.

.

.

.....[2]

Section B

Answer two questions in this section

5. (a) Explain what is meant by simple harmonic motion , and give an example of it thatoccurs in nature.

.[2]




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(b) A vertical peg is fixed to the rim of a horizontal turntable of radius r = 15.0 cm,rotating with a constant angular speed = 4.0 rad s -1, as shown in Fig. 5.1 below.

Fig. 5.1

Parallel light is incident on the turntable so that the shadow of the peg is observed ona screen, which is normal to the incident light. At time t = 0, = 0 and the shadow ofthe peg is seen at S .

At some later time t , the shadow is seen at T.

(i) Write down an expression for the angular displacement in terms of and t . [1]




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(v) Hence or otherwise, calculate 1. the speed of the shadow as it passed through S ,

speed of shadow = m s -1 [2]

2. the magnitude of the acceleration of the shadow when it isinstantaneously at rest

magnitude of acceleration =. m s -2 [2]

(c) A light spring hangs vertically from a fixed support and a metal sphere of mass

m is attached to its free end. The mass is displaced vertically and thenreleased. The variation of the kinetic energy of the mass E k, with time t of themass is shown in Fig. 5.2 below.

Fig. 5.2




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(i) Determine the period T of the oscillation.

period =.. s [1]

(ii) Using the data from the kinetic energy-time graph in Fig. 5.2 , sketch thedisplacement-time graph of the oscillating mass for two complete oscillationsusing the axes in Fig. 5.3 below.

On the axes, indicate and label clearly the amplitude and the period of theoscillation.

[2]

Fig. 5.3




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(d) To investigate the effects of damping on the oscillations of the metal sphere in (c) , anelectromagnet is placed near it, and light damping is observed.

(i) Explain what is meant by damping .

...[1]

(ii) Sketch on Fig. 5.2, the kinetic energy-time graph of the lightly dampedoscillating system.

[2]

(iii) Suggest how critical damping of the metal spheres oscillations may beachieved using the electromagnet.

...[2]




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(iii) Sketch a graph to show how the power dissipated in the light bulb connected tocoil Y varies with time over one cycle of the alternating output voltage.[2]

(b) Fig. 6.2 below shows the path of an -particle as it passes near the nucleus of a goldatom.

Fig. 6.2




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(i) Explain why the -particle was deflected as shown in Fig. 6.2 .

...[2]

(ii) Indicate on the diagram the direction of the electric force acting on the -particle.

[1]

(c) Xenon-139 has a half-life of 41 s and is generated at a constant rate during thefission of a specific sample of Uranium-235. The number of Xenon-139 nuclei in thesample increases initially and finally becomes constant.

(i) Explain the meaning of the following terms:

1. half-life,

...[1]

2. fission.

...[1]

(ii) Suggest a reason why the number of Xenon-139 nuclei in the sample becomes

constant.

...[1]




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(iii) The activity of Xenon-139 is 3.4 10 8 Bq when the number of Xenon-139nuclei has reached a constant.

Calculate

1.the number of Xenon-139 nuclei present in the sample.

number of Xenon-139 nuclei present =..[2]

2. the mass of Xenon-139 in the sample.

mass of Xenon-139 =kg [2]




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7. (a) Explain clearly each of the following observations:

(i) Light waves seem to travel only in straight lines while sound waves and waterwaves can go around corners.

...[2]

(ii) Sound waves cannot be polarized but radio waves can.

...[1]

(b) Fig. 7.1 below shows some of the possible energy levels of an electron orbitinginside a mercury atom.

The lowest possible energy level is Level 1. The diagram below is not drawn toscale.

Fig. 7.1




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(i) Explain how Fig. 7.1 can be used to account for the emission line spectrum .

......

...[3]

(ii) Cool mercury vapour is bombarded with a stream of electrons that have beenaccelerated from rest through a potential difference of 7.3 V.

1. Determine the kinetic energy of an electron inside the stream.

kinetic energy of electron =J [2]

2. Calculate the frequency of an emitted photon when an electron fallsfrom Level 2 to Level 1.

frequency of emitted photon =. Hz [2]




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3. State and explain whether photons with frequency in (b) (ii) (2) wouldbe emitted if electrons with energy of 4.15 eV collide with the mercuryatoms.

......

...[2]

4. Draw on Fig. 7.1 the number of possible transitions when the mercuryatoms are bombarded by electrons with energy of 7.6 eV.

[2]

(c) A particle of mass m and kinetic energy E has a de Broglie wavelength .

Show that the expression for de Broglie wavelength in terms of m and E is given by

2

h

mE =

[2]

(d) An electron travels at 0.5 times the speed of light.




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(i) Calculate its de Broglie wavelength.

de Broglie wavelength =. m [2]

(ii) Comment and explain what is observed if such an electron beam is passedthrough a thin film of crystalline material.

......

...[2]

END OF PAPER


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2010H2MI_Physics Prelim

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