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Physics Past Hsc Q’s Essay

Physics Centre Number Section I (continued) Part B – 55 marks Attempt Questions 21-32 Allow about 1 hour and 40 minutes for this part Student Number Answer the questions in the spaces provided. These spaces provide guidance for the expected length of response. Show all relevant working in questions involving calculations. Question 21 (2 marks) The optimum angle for safe re-entry of a space vehicle into Earth’s atmosphere is angle B. Outline consequences of the space vehicle entering the atmosphere at angle A AND angle C.

Space vehicle 2 A Atmosphere Earth NOT TO SCALE c 3431 -13- Question 22 (5 marks) An astronaut on the Moon throws a stone from the top of a cliff. The stone hits the ground below 21. 0 seconds later. The acceleration due to gravity on the moon is 1. 6 ms-2. 300 m (a) Calculate the horizontal component of the stone’s initial velocity. Show your working. -? Calculate the vertical component of the stone’s initial velocity. Show your (c) On the diagram, sketch the path that the stone would follow if the acceleration due to gravity was higher. The initial velocity is the same. 1 -14- Board of studies NEWS 2010 Centre Number Section I – Part B (continued) Student Number Question 23 (5 marks) A train is traveling on a straight horizontal track. A student on the train attaches a mass on a string to the ceiling of the train. The student observes that the mass remains stationary in the position shown. Mass Why does the mass hang with the string at an angle to the vertical? The string then breaks and the mass falls. Indicate the path of the mass on the diagram above. Explain why the mass has taken this path. 3 3432 -15-

Question 24 (3 marks) In 2014 the James Webb Space Telescope STOWS) will be placed in orbit around the Sun. Earth and the JUST will follow the orbits shown, with identical orbital periods. This appears to contradict Keeper’s law of periods. 3 Sun Earth JUST NOT TO SCALE Why is it possible for the JUST to orbit the Sun with the same orbital period as Earth? In your answer, refer to Keeper’s law of periods. -16- Question 25 (4 marks) The mass of a rocket decreases during launch as it burns fuel, as shown in the graph. The rocket engine produces a constant upward force on the TTL (a) Time 2

Question 28 (4 marks) A copper rod is placed on a wooden frame, which is placed on an electronic balance. A length of 0. 2 m of the rod passes at right angles to a horizontal magnetic field. Magnetic field 0. 2 m 0. 3 A insulating frame 4 Electronic balance When a current of 0. 3 A is passed through the rod, the reading on the balance increases by 7. 5 x 10-4 keg. What is the strength and direction of the magnetic field? . 3434 -21- Question 29 (3 marks) Two sets of plates deflect an electron beam in a cathode ray oscilloscope to produce the trace on the screen as shown.

Explain how the deflection plates produce this pattern. Question 30 (5 marks) Pure germanium can be doped by adding small amounts of boron. (a) Is the doped germanium an n-type or a p-type semiconductor? Justify your answer. (b) Explain how the addition of boron alters the electrical conductivity of germanium. … 32 3435 Question 31 (5 marks) (a) What is the energy of a photon having a wavelength of 1 oho NM? . (b) Explain why light having a wavelength longer than a certain value does not produce an electric current in a photocell. -? 32 -24-

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