HCI SPECIMEN PAPER A Higher Paper

1 Name: __________________________________ ( ) Class: _______ HWA CHONG INSTITUTION SPECIMEN PAPER A HIGHER PHYSICS Level: Secondary Three Duration: 1 hour INSTRUCTIONS TO CANDIDATES Do not open this booklet until you are told to do so. Write your name, index number and class on the top of this page. Answer the questions in Section A and B in the spaces provided. All workings must be shown. In Section B, answer only 2 questions out of the 3 questions. INFORMATION FOR CANDIDATES In Sections A and B the intended marks for each question or part of a question are given in brackets [ ]. Any working should be done in the space provided. When necessary, take acceleration due to gravity, g to be 10 m s-2. This question paper consists of 12 printed pages, including this page.

2 Section A [20 marks] Answer all the questions in this section. 1 An elastic collision is defined as one in which there is no loss of kinetic energy in the collision. An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision. An experiment to investigate coll isions has been set up as shown in figure A below. Two motion sensors are set up at each end of the runway. Trolley A is given a sharp push so that it runs along the runway and collides with trolley B. Figure B shows the velocity time graph of the motion o f the two trolleys. Both trolleys are of mass 500 g. (a) Estimate the distance moved by trolley A before collision. [2] (b) Explain why the velocity of one of the graphs is negative. [1] …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. Figure A Figure B

3 (c) What is the average force acting on trolley A during the collision? [2] (d) A student wrote the following observation in his lab report. Momentum before collision = 0.500 x 0.35 = 0.18 kg m s-1 Momentum after collision = 0.500 x 0.30 = 0.150 kg m s-1 Since momentum before collision is not equal to the momentum after collision, hence momentum is not conserved. Comment on the student’s observation. [2] …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. (e) Explain with evidence if the collision between the trolleys is elastic or inelastic. [3] …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. ………………………………………………………………………………………………………….

4 2 Sea level rises provide one of the most immediate and direct consequences of global warming. A major contribution to sea level rise is thermal expansion of sea water. About 70% of the Earth’s surface is covered with water and the average depth is about 3.8 km. The coefficient of volume expansion β, is defined as the fractional change in volume per unit change in temperature in Kelvin. ∆ V = βV0∆T where ∆V is the change in original volume V0 caused by a temperature change ∆T. Water has a rather unu sual expansivity, it contracts when heated from 0°C to 4°C before expanding. Since expansion of sea water is non -linear, the coefficient of volume expansion for water is not constant. The graph below shows the coefficient of volume expansion in SI unit for water at various temperatures. (a) On the graph above, draw the best-fit line for the data points. [1] (b) State if the graph suggests that temperature T and the coefficient of volume expansion β are related by an expression of the form T = a β + c where a and c are constants. [1] …………………………………………………………………………………………………………. ………………………………………………………………………………………………………….

5 (c) Deduce the unit for volume expansivity. [1] (d) Estimate the total volume of water on Earth. [3] (e) If the temperature of the sea water is currently at 20°C, (i) calculate the approximate increase in volume of sea water if the average temperature of the sea water rose by just 1.0 °C. [2] (ii) Predict the rise in sea level which would result from the increase in temperature of just 1.0 °C. [1] (f) Explain a possible impact on Singapore due to rise in sea level. [1] …………………………………………………………………………………………………………. ………………………………………………………………………………………………………….

6 Section B [20 marks] Answer two out of three questions in this section. 3 Animals have different eye structures to enable them to see and be able to survive in their natural habitat. Several eye structures are shown in the diagram below. Rays of light from two points of a distance object are incident into the eyes. (a) A snail is only able to tell which direction light is coming from but cannot form an image, which eye structure does the snail have? [1] …………………………………………………………………………………………………………. (b) Describe the vision of the animal having eye structure Q. [1] …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. P Q R S

7 The figure below shows an image formed by a single spherical surface (similar to eye structure R) separating media of refractive index n1 and n2. If the radius of curvature of the surface is r, then the focal length f, the distance from the centre of curvature C to the focus F is given by: f= n1r (n2-n1) (c) By applying Snell’s law to the refracted ray and given that OF is approximately the same as f + r, show that f = n1r (n2-n1) [4] C F f r n2 n1 O

8 (d) Explain the difference in the focal length of the eye when light rays enter the eye from air and water. [2] …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. …………………………………………………………………………………………………………. (e) The material in the eye structure R has a refractive index 1.40 and a focal length of 10 cm in air. Determine the focal length in water when the eye is completely in seawater of refractive index of 1.35. [2]

9 4 Next to the 3000-year-old Drombeg circle in Ireland is a stone-lined pit known as a Fulacht Fiadh. A fulacht fiadh is the name given to an ancient cooking pit dating from the Bronze Age. Fulachta fiadh is generally located beside a source of water, a pit o r hole was constructed and filled with clean water. Archaeology thinks that during that time, water was first heated by placing heated stones in it and fresh meat was then boiled in it. In an experiment to test this idea , it was found that the 120 kg of water in the pit of initial temperature of 18°C started to boil after five heated stones each of average mass 9.0 kg had been added. Specific heat capacities of stone and water are 1.1 J g–1 °C–1 and 4.2 J g–1 °C–1 respectively. Fresh meat cut into a cube of 10.0 cm length was then lowered into the boiling water. Energy is transferred by conduction when the piece of meat comes into contact with the heated water. The basic thermal energy transfer equation for conduction is given by Q t = kA∆T d where Q is the amount of energy transferred, t is the time taken, A would be the area of the piece of meat , k the thermal conductivity of the meat 0.496 W m -1°C–1, ∆T is the difference in temperature and d is the thickness of the piece of meat. (a) Determine the minimum temperature for the fire. [2]

10 (b) Explain why the temperature o