GIRLS SECONDARY MRIEĦEL HALF YEARLY EXAMINATION 2015/2016 TIME: 1½hrs FORM 3 Track 2 Name: Class: Index: Notes for candidates: Answer all the questions. Write down your answers in the spaces provided. The use of a calculator is allowed. Whenever necessary take g to be 10N/kg. Formulae that can be used are listed below: Measurements V = l x b x h A = l x b Density Forces ρ = m V W = mg Pressure P = F A P = hρg Moments Moment = Force x perpendicular distance from the pivot For office use only Question No. 1 2 3 4 5 6 7 8 Theory Practical Mark Final Mark Maximum Mark 8 8 8 8 8 15 15 15 85 15 100 Score Page 1 of 12
Section A - This section carries 40 marks Question 1: This question is about measurements (1mark for each answer) a. Complete the following i. 250m = cm ii. iii. 0.35kg = g 2hrs = minutes = seconds b. Martha needs to do an experiment in the lab: i. To find the volume of some water, she uses a. ii. iii. To find the mass of a small rock, she uses a. To find the volume of a large rock, she uses a. c. Alessandro is interested in doing a marathon. To keep track of his speed he needs to record the distance and the time. An appropriate apparatus used to measure the time is a. Question 2: This question is about density (Total: 8 marks) a. Complete the following table (show your working in the lines provided): Mass (g) Volume (cm 3 ) Density (g/cm 3 ) 200 17.64 9.8 7.85 (2 marks for each answer) Page 2 of 12
Name: Class: b. Luca was given a pendant with a back and front surface area as shown in the diagram below. (Note: Diagram is not to scale) 1cm i. Use the diagram to find the front surface area of the pendant 3cm 2cm 1cm (1 mark) ii. If the thickness of the pendant is 0.02cm, find the volume of the pendant. (1 mark) iii. If the mass of the pendant is 19.3g, find the density of the pendant. (2 marks) Question 3: This question is about pressure a. A student with a mass of 60kg falls asleep on his four-legged chair of mass 5kg. Each leg of the chair has a surface area of 0.0002m 2 in contact with the ground. (Total: 8 marks) i. Find the total WEIGHT of the student and the chair together. (2marks) Page 3 of 12
ii. Find the total surface area of the chair in contact with the ground. (1mark) iii. Hence, find the pressure exerted by the student and chair on the ground. (3 marks) b. Which of the following statements shows the highest pressure upon the ground? (Mark your answer with an X ) A 7000-kg elephant with total area 0.5m 2 in contact with the ground (2 marks) A 65-kg lady in high heels with total area 0.005m 2 in contact with the ground (Total: 8 marks) Question 4: This question is about forces a. Tick whether the following statements are TRUE or FALSE (4 marks) STATEMENT TRUE FALSE Friction is a force which occurs between two surfaces rubbing against each other. Weight is a vector quantity. Our weight on the moon does not change; it is our mass which changes. On a flying plane there is no gravitational force. Page 4 of 12
Name: Class: b. The diagram below shows a stationary car, draw and label the forces acting on the car: (3 marks) c. Find the resultant force acting on the rope shown below, stating its size and direction. Resultant force = (1 mark) (Total: 8 marks) Page 5 of 12
Question 5: This question is about moments The diagram below shows a uniform metre ruler AB resting at its centre on a pivot. A weight of 20N is placed 0.3m away from the pivot. Another weight X is placed 0.4m away from the pivot on the opposite side to keep the rule in equilibrium. 0.3m 0.4m A B 20N X a. Calculate the size of weight X: (3 marks) b. Underline the correct answer: (5 marks) i. The direction of the moment created by weight X is (clockwise, anticlockwise). ii. iii. iv. The sum of the total clockwise moments is (greater than, equal to, smaller) than the sum of the total anticlockwise moments. If the distance of X from the pivot is reduced to 0.2m, for the system to remain in equilibrium, the distance of the 20N force from the pivot must be (0.15m, 0.10m). If weight X is doubled, for the system to remain in equilibrium, the 20N force must be replaced by another one of size (10N, 40N). v. If weight X is halved, for the system to remain in equilibrium, the 20N force must be replaced by another one of size (5N, 10N). (Total: 8 marks) Page 6 of 12
Section B - This section carries 45 marks Question 6: This question is about pressure Two physics students were doing an experiment to prove that in a liquid pressure increases with depth. Using a pressure sensor and a large measuring cylinder filled with liquid, they managed to obtain the following results: Pressure by liquid (Pa) Height of liquid (m) 0 0.5 1.0 1.5 2.0 3.0 0 0.05 0.10 0.15 0.20 0.30 a. On a graph paper, use the above results to plot a graph of Pressure (Pa) on the y- axis against Depth (m) on the x-axis. b. Using any two values from the table and the equation P = hρg, calculate the density of the liquid. (4marks) (3marks) c. Using the graph, find the pressure in the liquid be at a depth of 0.35m. (1mark) d. Using the graph, find the depth of liquid when the pressure gauge reads 2.5Pa (1mark) Page 7 of 12
e. Mark as True (T) or False (F): i. If the experiment had to be repeated with a less dense liquid, the values for the pressure should decrease. ii. iii. If the same experiment is repeated on another planet where the gravity is less than 10N/kg, the values for the pressure decrease. If the same experiment had to be done using a wider measuring cylinder the values for the pressure would not be affected. (3 marks) f. The students found the information shown below on the internet: Liquid Density Oil 0.95 kg/m 3 Orange juice 1.1 kg/m 3 Water 1.0 kg/m 3 Which liquid must have been used for this experiment? (1mark) g. There is a pressure which acts on everything around us even outside the liquid. i. What is the name of this pressure? (1 mark) ii. What causes it? (1 mark) (Total: 15 marks) Page 8 of 12
Question 7: This question is about moments Paul found a uniform meter ruler weighing 0.5N. He also found some string, a small empty tin, and some 100g masses. Paul set the respective equipment as shown in the diagram below: String 100g Masses Tin 30cm Ruler a. Mark clearly, with the letter C, the centre of gravity of the ruler. (1 mark) b. For a system in equilibrium, the law of moments states that the total moment must be to the total anti-clockwise moment. (2 marks) c. Paul filled the empty tin with water until the total weight of tin and water is 3N. Then he placed it 30cm away from the string as shown in the diagram. Calculate the distance at which he has to place 2 of the masses (total of 2N) to balance the ruler. (4 marks) d. On the above diagram mark with an arrow the existing tension force and label it T. (1 mark) Page 9 of 12
e. Calculate the size of this tension force when the system is in equilibrium. Remember that the weight of the ruler is 0.5N (2marks) f. Paul now added another 100g mass on the previous two, for a total weight of 3N at the same distance from the pivot as before. Calculate the new weight of water and tin that Paul needs to have in order to balance the system again. 3N 30cm?N (4 marks) g. Paul then removed all the masses and the tin from above the ruler. After removing everything, does the ruler remain balanced? (1 mark) (Total: 15 marks) Page 10 of 12
Question 8: This question is about Hooke s Law a. Complete the following statement using the following words. (3 marks) proportional extension exceeded Hooke s Law states that the force applied is directly to the, unless the elastic limit is. b. What happens to a spring when the elastic limit is exceeded? (1 mark) c. On the diagram provided, label the set up needed to perform an experiment to prove Hooke s Law. (4 marks) d. Complete the following: (2 marks) The was set up as shown in the diagram. The length of the spring was measured and recorded in the table below. A 1N weight was hung and the new of the spring was recorded. These two values were subtracted and the of the spring was found. This procedure was repeated with different weights. Page 11 of 12
e. Complete the following table: (2 marks) Applied force (N) 0 1 2 3 Length of spring (cm) 5 7 9 11 Extension (cm) f. Write two precautions to ensure an accurate result. (2 marks) g. Mark with a letter E on the graph below the elastic limit (1 mark) Extension (cm) Weight (N) (Total: 15 marks) Page 12 of 12