SIR MICHELANGELO REFALO SIXTH FORM Annual Exam 2014 Subject: PHYSICS INT. 1 st Year Time: 2 hrs. Answer All Questions Where necessary assume the acceleration due to gravity, g = 10m/s 1) A basketball player throws a ball with an initial velocity of 6.5m/s at an angle of 50 to the horizontal. The ball is 2.3m above the ground when released. a) Calculate the horizontal and vertical components of the initial velocity of the ball. b) Show that the time taken for the ball to reach the basket is 0.69s. c) Calculate the maximum height from the ground reached by the ball. [6, 2, 5 marks] Page 1 of 5
2a) Define work done by a force. b) The diagram below shows a water slide. The top of the slide is 32m above the bottom of the slide. The total distance along the slide is 120m. A person of weight 700N, initially at rest at the top, slides down. His speed at the end of the slide is 15m/s. i) Calculate the kinetic energy at the end of the slide. ii) Calculate the average resistive force acting on him as he travels down the slide. [2, 3, 7 marks] 3) A sample of wire is tested in the laboratory. The figure below shows how the extension varies with the force applied. a) State what the gradient of the graph represents. Page 2 of 5 e/x10-3 m b) The initial length of the wire of diameter 0.56mm is 1.60m. Use the graph and this information to determine the Young s modulus of the material of the wire. c) The test is repeated for another wire of the same material and length but half its diameter. Explain how the force against extension graph for this wire would differ from the above. Justify your answer. [2, 7, 4 marks]
4a) In general the value of the latent heat of vaporisation of a substance is much greater than the latent heat of fusion. Explain. b) A 2kW immersion heater is switched on for 10 minutes to heat 2.5kg of water at a temperature of 15 o C. i) What is the amount of heat energy supplied by the heater during this time? ii) How much energy is absorbed by the water to reach its boiling point? iii) Hence, find the mass of water converted into steam. iv) State two important assumptions in your calculations. [Specific heat capacity of water = 4200J/kg K; Specific latent heat of vaporisation of water = 2.26x10 6 J/kg] [2, 3, 4, 4 marks] 5) The circuit below consists of a battery of negligible internal resistance, two resistors and a thermistor. The thermistor has a resistance of 360Ω at a temperature of 20 o C. a) What is the current in the circuit? b) What is the potential difference across the thermistor? c) Describe how the potential difference across the thermistor and the current flow in it will vary as the temperature rises. Justify your answers. [6, 3, 4 marks] Page 3 of 5
6) The base of a thundercloud is 489m above an area of open flat ground as shown below. The uniform electric field strength between the cloud and the ground is 7.2x10 4 N/C. a) Explain what is meant by a uniform electric field. b) Draw the electric field between the cloud and the ground. Show the direction of the electrical force acting on an electron between the cloud and the ground. c) Calculate the potential difference between the cloud and the ground. d) During a lightning strike, a charge of 5.0 C passes between the cloud and the ground in a time of 348µs. The strike has a negligible effect on the potential of the cloud. Calculate the average power of the lightning strike. [3, 3, 3, 6 marks] GO TO THE NEXT QUESTION Page 4 of 5
7) In an experiment to determine the mass per unit length (µ) of a copper wire, the apparatus shown below is used. The wire is kept under a constant tension (T) by means of a constant weight of 10N. A horse shoe magnet is placed half way along its length and the ends of the copper wire are connected to a low voltage alternating current supply. The frequency (f), of the alternating current is varied until the wire vibrates with large amplitude. The experiment is repeated for different lengths (L) and the corresponding resonant frequency is recorded. f/hz L/m 100 0.62 95 0.65 90 0.70 85 0.75 80 0.78 1 /m -1 L The length L is related to the resonant frequency f by the equation: f 1 2L T a) Copy the table and fill the missing values. b) Plot a graph of f /Hz against L 1 /m -1. c) Find the gradient of the graph and give the base units of the gradient. d) Use the value of the gradient to determine the mass per unit length of the wire, explaining clearly your working. [3, 9, 5, 4 marks] Page 5 of 5