THE ANGLO-AMERICAN SCHOOL OF SOFIA

2012-2013 Year End Exam

Student name: _________________________________________

SUBJECT / level IB1 HL Physics Paper Two

GRADE 11

DATE June 17, 2013

TIME 80 minutes

TEACHER Ms. Henderson

INSTRUCTIONS • Do not open this examination paper until instructed to do so.

• Answer all of the questions in the spaces provided.

•Data Booklet and calculators are allowed.

Total 63 marks

Accredited by – The New England Association of Schools & CollegesThe European Council of International Schools

1. A student is investigating kinetic energy. He sets up the apparatus as shown.

The trolley starts from rest with the weight close to the pulley and at a height h above the floor.(a) Describe how you would measure the height h. You may add to the diagram if you wish. [1]

(b) The student records the distance h and the time t it takes for the weight to fall to the floor. His measurements are shown below.

h = 885 mm

The maximum velocity of the trolley is given by2ht

(i) Estimate the uncertainty in the value for h. This should relate to your method in part (a). [1]

(ii) Estimate the uncertainty in the readings for t. [1]

(iii) Calculate the mean maximum velocity. [1]

(iv) The mass of the trolley is 0.930 kg and the falling weight has a mass of 0.030 kg. Calculate a value for the total maximum kinetic energy of the trolley and weight. [1]

(v) Estimate the percentage uncertainty in your calculated value for the kinetic energy.Assume the uncertainty in the values of both masses is negligible. [2]

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2. A satellite uses a radium-226 source as a back-up power supply. Radium-226 is an alpha particle emitter.

(a) The satellite requires a back-up power of 55 W. Each alpha particle is emitted with an energy of 7.65×10-13J. Show that the activity of the source must be about 7×1013Bq. [2]

(b) Radium-226 has a half-life of 1620 years. Show that its decay constant is about 1.4 × 10-11 s-1. [2]1 year = 3.15×107s

(c) Hence determine the number of radium-226 nuclei that would produce the required activity. [2]

(d) Calculate the mass of radium-226 that would produce a power of 55 W. 226 g of radium-226

contains 6.02 × 1023 nuclei. [2]

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3. The graph below shows how the maximum kinetic energy of the electrons varies with the frequency of the light shining on the metal surface.

(a) (i) On the graph mark the threshold frequency and label it fo. [1]

(ii) On the graph draw a line for a metal which has a higher threshold frequency. [2]

(iii) State what is represented by the gradient of the graph. [1]

(c) The threshold frequency of a particular metal surface is 5.6 × 1014Hz. Calculate the maximum kinetic energy of emitted electrons if the frequency of the light striking the metal surface is double the threshold frequency. [3]

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4. A long strip of springy steel is clamped at one end so that the strip is vertical. A mass of 65 g is attached to the free end of the strip, as shown in Fig. 2.1.

The mass is pulled to one side and then released. The variation with time t of the horizontal displacement of the mass is shown in Fig. 2.2.

The mass undergoes damped simple harmonic motion.(a) (i) Use Fig. 2.2 to determine the frequency of vibration of the mass. [1]

(ii) Hence show that the initial energy stored in the steel strip before the mass is released is approximately 3.2mJ. [2]

(b) After eight complete oscillations of the mass, the amplitude of vibration is reduced from 1.5 cm to 1.1 cm. State and explain whether, after a further eight complete oscillations, the amplitude will be 0.7cm. [2]

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5. The photograph shows an arrangement used to launch a light, foam rocket at a school science competition.

The rocket is launched at the level of one end of a long table and lands at the other end at the same level. The students measure the horizontal distance travelled by the rocket and the time of flight.(a) The rocket travels 1.88 m in a time of 0.88 s.(i) Show that the horizontal component of the initial velocity of the rocket is about 2 m s -1. [2]

(ii) Show that the vertical component of the initial velocity of the rocket is about 4 m s -1. [2]

(b) The students obtained their data by filming the flight. When they checked the maximum height reached by the rocket they found it was less than the height predicted using this velocity. Suggest why the maximum height reached was less than predicted. [1]

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6. A diffraction grating was used with a spectrometer to obtain the line spectrum of star X shown in Figure 7. The diffraction grating used to obtain the spectrum of star X had 300 slits per mm.

(a) Calculate the distance between the centres of two adjacent slits on this grating. [1]

(b) Calculate the first order angle of diffraction of line P in Figure 7. [2]

AQA-PHYA2-jun10#6

7. Figure 3 shows an X-ray spectrum produced by an X-ray tube when an accelerated electron beam is incident on a tungsten target. It shows a continuous spectrum with peaks at certain wavelengths.

(a) (i) Calculate the photon energy, in J, that corresponds to peak A. [3]

(ii) use data from the graph to calculate the maximum energy of the electrons in the beam. [2]

(iii) explain why there is a maximum value. [1]

AQA-PHYB4-Jun11#5

8. (a) Explain the difference between the loudness and the intensity of a sound. [2]

(b) An observer measures the intensity of a sound wave at a distance of 1.5 metres from a source to be

2.0 × 10-10 Wm-2. The observer then moves to a position where the intensity is measured to be 2.5 × 10 -11

Wm-2. Calculate how far from the source the observer is when the intensity is measured to be 2.5 × 10 -11

Wm-2. [3]

(c) Calculate the increase in the number of decibels which would be needed to restore the intensity measured by the observer in this new position to 2.0 × 10-10 Wm-2. [3]

AQA-PHYB1-Jan09#6

9. (a) An ultrasound investigation is carried out on a liver, which is at a depth of 12 cm below the skin of a patient. Show that the time taken between transmitting a pulse into the body and receiving the reflected pulse from the surface of the liver is approximately 0.2 ms. Assume that the speed of sound in the human body is 1500 m s-1. [2]

(b) Hence calculate the maximum rate at which the pulses should be produced by the ultrasonic transducer. [2]

(c) A higher frequency of ultrasound is used when imaging an eye compared to when imaging a liver. Explain why higher frequencies are preferred for imaging structures near the surface of the body but would be unsuitable for imaging structures deeper within the body. [3]

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10. This question is about wedge film interference.One flat, glass slide is placed at an angle on top of a second identical slide. The slides are in contact along one short edge and are separated at the other edge by a thin piece of paper, as shown below.

A thin wedge of air of variable thickness, t, is trapped between the two slides. The arrangement is viewed normally from above, using light of wavelength 590 nm. The glass plates are coated, so that reflection only takes place at the bottom surface of the top plate and the top surface of the bottom plate.

A series of straight bright and dark fringes, equally separated and parallel to the short edge of the slides, is seen.

(a) Deduce that the thickness of the air wedge t that gives rise to a bright fringe, is given by

2 t=(m+ 12 ) λ [2]

(b) The length of the air wedge, L, is 8.2cm. The bright fringes are each separated by a distance of 1.2 mm. Calculate the thickness of the paper. [3]

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