HALF YEARLY EXAMINATIONS 2016/2017. Answer ALL questions showing your working Where necessary give your answers correct to 2 decimal places.

Transcription

1 Track 3 GIRLS SECON DARY, MRIEHEL HALF YEARLY EXAMINATIONS 2016/2017 FORM: 4 PHYSICS Time: 1½ hrs Name: Class: Answer ALL questions showing your working Where necessary give your answers correct to 2 decimal places. Table of Formulae Acceleration due to gravity g = 10 m/s² Average speed = total distance v = u + at a = (v u) total time t s = ut + ½at 2 s = (u + v)t v 2 = u 2 + 2as 2 Refractive index n = real depth Refractive index n = speed of light in air apparent depth speed of light in other medium Magnification = height of image = image distance from lens height of object object distance from lens Speed of wave v = fλ Periodic time T = 1 f Area of a triangle = ½bh Area of a trapezium = h(a + b) 2 For examiners use only Question Theory Practical Total Max. Mark Score Physics Form 4 Page 1 of 9 Half-Yearly T3/

2 SECTION A This section carries 40 marks 1. This question is about optics a) The diagram shows a ray of light incident onto a plane mirror AB. i) OX is the ray while OY is the ray. [1] ii) Find the angle of incidence i. [1] iii) What is the angle of reflection r? [1] A X 55 iv) Tamara wrote some notes from her observations, some of which are wrong. Identify which statements are true and which are false. [3] O i r N Y B Statement i) If the angle of incidence is 45⁰, the angle of reflection should be double the size. ii) The normal should be drawn at 90⁰ to the plane mirror. iii) Reflection occurs when waves pass from one medium to another. True/False b. Complete the following diagram showing the refracted and emergent rays. [2] incident ray air glass air 2. This question is about the equations of motion. A van travelling with an initial velocity of 72 km/h skids to a stop, moving a distance of 25 m. a) Find the initial velocity of the van in m/s. [2] b) What is the final velocity of the van? [1] Physics Form 4 Page 2 of 9 Half-Yearly T3/

3 c) Calculate the deceleration of the van. [3] d) Find the time it takes to stop. [2] 3. This question is about motion Ruth decides to use the apparatus shown in the diagram to find a value for the acceleration due to gravity g. a) She uses a particular method to find the value of g. Indicate the order of numbers 2 to 4 in which the steps of the experiment have to be performed. [3] Pad Electromagnet Ball bearing Photodiode stand The apparatus was set up as shown. 1 The digital timer stops as the metal ball passes in front of the photodiode. The metal ball is attached to the electromagnet. As the switch is closed, the metal ball falls and the electronic timer starts. Ruth then proceeds to do the experiment. b) The initial speed of the ball bearing is [1] c) Ruth uses a to measure the height fallen by the metal ball. [1] d) She then decides to repeat the experiment using a heavier metal ball together with a stopwatch to measure the time taken by the ball to fall. i) Does a heavier metal ball make a difference in the measured value of g? Why? [2] ii) Using a stopwatch instead of the electronic timer is not such a good idea. Why? [1] Physics Form 4 Page 3 of 9 Half-Yearly T3/

4 4. This question is about optics During a Physics lesson, John and Maria were supplied with an optical bench as shown in the diagram. object convex lens image Light source X Y a) Which distance, X or Y represents the: (i) object distance, [1] (ii) image distance [1] b) The two students use a convex lens having a focal length of 2 cm. They vary the object distance u and measure the corresponding image distance v. The table shows the reading obtained by the students and the corresponding magnification m in each case. Object distance u/cm Image distance v/cm Magnification m c) Fill in the two missing numbers in the table. [2] d) Plot a graph of magnification m on the y-axis against the image distance v on the x-axis. Draw the best straight line through the points. [4] 5. This question is about velocity time graphs. A car is travelling at 25 m/s. The driver realises that he has to decelerate immediately and stop the car as a pedestrian was going to cross the road. The driver applies the brakes and stops the car. a. On the graph, label the part AB where the driver is driving at constant speed. [1] Physics Form 4 Page 4 of 9 Half-Yearly T3/

5 b. Using the graph, calculate the thinking distance travelled by the car. [2] c. Find the deceleration of the car. [2] d. Using the graph, find the braking distance of the car. [2] e. Hence find the total stopping distance of the car. [1] SECTION B This section carries 45 marks 6. This question is about Waves a. Label diagrams 1 and 2 with the appropriate words given in box below: wavelength amplitude crest trough compression rarefaction [3] Diagram 1 Diagram 2 From the above diagrams, answer the following questions: b. Which of the diagrams represent a transverse wave? [1] c. Which of the diagrams represent a longitudinal wave? [1] d. Mention two differences between transverse and longitudinal waves. [2] Physics Form 4 Page 5 of 9 Half-Yearly T3/

6 e. Look carefully at the diagram below and answer the following questions: i. Write down the periodic time of the wave. [1] ii. Calculate the frequency of the wave. [1] iii. If the speed of the wave is 330 m/s, calculate the wavelength of the wave. [2] iv. Fill in the missing words in the following table: [2] Gamma Rays Infra Red Rays Radiowaves f. Ultrasound waves have a very high frequency beyond human hearing range. However, these sounds are very much used by animals such as bats and dolphins. Humans too make use of these sounds when studying the seabed or to track any sunken vessels. The diagram shows a vessel using the echo sounder to determine the depth of the sea. If a pulse was sent to the seabed and took 20 s to return back, calculate the depth of the sea if the speed of sound in water is m/s. [2] Physics Form 4 Page 6 of 9 Half-Yearly T3/

7 7. This question is about light waves. (a) Mia shines a ray of light on a glass prism. She wants to investigate what happens when white light passes through this prism. white light screen i. Complete the diagram to show how the red and the violet colours are produced on the screen. Write R for red and V for violet at the place where these colours would be seen. [3] ii. Which one of these two colours is the least refracted? Explain why. [2] (b) Mia then investigates how a periscope works. This periscope consists of two glass prisms. The critical angle of glass is 42. A object B i. Name the effect taking place at points A and B. [1] ii. Write down the two conditions for this effect to take place. [2] Physics Form 4 Page 7 of 9 Half-Yearly T3/

8 (c) Mia then experiments with a convex lens. She placed an object 1 cm high 5 cm in front of the lens. The lens has a focal length of 3 cm. Note: 1 square represents 1 cm. O F F i. Complete the ray diagram showing how the image of the object is produced. [3] ii. Write down two characteristics of the image formed. [2] iii. Measure the image distance. [1] iv. Give one use for such a lens. [1] 8. This question is about Freefall Sarah drops a piece of plasticine of mass 135 grams from a height of 8 m above the ground. a. Draw the two forces acting on the plasticine as it is falling to the ground. [2] plasticine b. What is the initial velocity of the stone? [1] c. What is the mass of the plasticine in kg? [1] d. What is the initial acceleration of the plasticine as it falls to the ground? [1] e. What is this acceleration called? [1] f. Calculate the time taken for the plasticine to reach the ground. (ignore air resistance) [3] Physics Form 4 Page 8 of 9 Half-Yearly T3/

9 g. Find the velocity just before the plasticine hits the ground. (ignore air resistance) [2] h. Sarah decides to attach a small parachute to the piece of plasticine. Explain any change in the time taken to reach the ground? [2] i. Sarah repeats the experiment using a piece of plasticine of mass 350 grams. Assuming that no opposing forces act in both cases, explain any difference, if any, would there be in the final velocity of the larger piece of plasticine. [2] END OF PAPER PLEASE CHECK YOUR WORK! Physics Form 4 Page 9 of 9 Half-Yearly T3/