SNGS P3 PRACTICAL WS + MS (graphing, planning)

1 CHIJ ST. NICHOLAS GIRLS’ SCHOOL R7 Practical Revision Name : ___________________ ( ) Class :___________ Date: __________ 1. Plotting and Analysing G raph (a) In an experiment, a student investigate how the voltage V across a resistance wire changes with length x of the wire. The table below shows the data collected by the student. x / cm V / V 10.0 0.20 15.0 0.30 25.0 0.40 35.0 0.55 45.0 0.70 60.0 1.90 65.0 2.00 75.0 2.20 85.0 2.30 90.0 2.40 (i) Using the grid provided, plot a graph of V against x. Start your axes at the or igin (0,0). The x- axis must start from 0 cm and end at 100 cm. Draw two lines of best fit, • one for x = 10 cm to x = 45 cm, label this A. • one for x = 60 cm to x = 90cm, label this B. (ii) Determine the gradient GA of line A. and the p.d. VA when x = 0 cm for line A. 𝐺𝐴 = 1.01−0.10 70−0 = 0.91 70 = 0.013 VA = 0.10 V (iii) Determine the gradient GB of line B. and the p.d. VB when x = 0 cm for line B. 𝐺𝐵 = 2.40−1.40 90−26 = 1.00 64 = 0.016 VB = 0.98 V

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3 2. Planning (a) A student investigates the stability of a stand. She set up the apparatus as shown in the diagram below . She pulled the newton -meter horizontally until the edge A starts to rise and recorded the value of the force F. Fig. 1 When the edge A of the stand just starts to rise, the following equation applies: W x = F y where • W is the weight of the stand • x is the horizontal distance of the centre of gravity of the stand from the edge B. The above equation can be re-written as 𝐹 = 𝑊𝑥𝑦 The weight of the stand is 22.4 N. Use the same apparatus to plan an experiment to investigate the relationship. Your plan should include: • the quantities that you will keep constant, • a detailed description of how you will perform the experiment, • a suitable table in which to display your measurements and calculated values (you do not need to enter any data into the table), • a statement of the graph that you would plot to test the relationship, • a sketch of the graph that you would obtain if the suggested relationship is correct, • an explanation of how you would obtain a value of x from your graph.

4 In this experiment, the independent variable is y, and the dependent variable is F. The controls in this experiment are angle between the rod of the retort stand and line of action of F (to be maintained at 90o), and the direction of F (such that the position of the pivot stays at edge B) . 1. Set up the apparatus as shown in Fig. 1. 2. Place the loop of thread on the retort stand at a distance y = 60.0 cm. 3. Determine the value of 1 𝑦. 4. Pull the newton-metre horizontally until the edge A start to rise and record the force F. 5. Throughout the experiment, the newton metre must remain horizonal and the pivoting point is at B. 6. Repeat steps 1 to 5 for different values of y such that there is a total of 6 sets of readings. 7. Tabulate the measured and calculated data as shown below. y / cm 1 𝑦 / 𝑐𝑚−1 F / N 8. Plot a graph of F / N against 1 𝑦 /𝑐𝑚−1. 9. Calculate the gradient G of the graph. 10. Since G = W x, x can be calculated by 𝐺 22.4. F / N 0 1 𝑦 / cm-1

5 (b) A student investigates how the mass of crushed ice affects the temperature dro p of water. For the first set of data, he placed a heaped spoonful of crushed ice at 0 C into 100 cm 3 of water at room temperature R. When all the crushed ice in the beaker has melted, he measures and records • the final volume of water Vf • the volume of water that has formed from the melted ice Vi • mass of melted ice mi , given that 1 cm3 of water has a mass of 1 g. • final temperature of the water. A suggested relation of the mass of melted ice mi and temperature change of water (𝜃𝑅 − 𝜃𝑓) is 336 𝑚𝑖 = 100𝑐𝑤(𝜃𝑅 − 𝜃𝑓) where mw is the mass of 100 cm3 of water, and cw is the specific heat capacity of water. Using the same apparatus, plan an experiment to investigate the relationship. Your plan should include: • the quantities that you will keep constant, • a detailed description of how you will perform the experiment, • a suitable table in which to display your measurements and calculated values (you do not need to enter any data into the table), • a statement of the graph that you would plot to test the relationship, • a sketch of the graph that you would obtain if the suggested relationship is correct. • an explanation of how you would obtain a value of the specific heat capacity of water cw from your graph.

6 In this experiment, the independent variable is the mass of the ice to be melted, and the dependent variable is the temperature change of the water. The controls in this experiment are the initial volume of the water in the beaker (100 cm3), and the room temperature. 1. Measure 100 cm3 of water with a measuring cylinder. Pour the water into a beaker. This initial volume of the water in the beaker is to be kept constant throughout the experiment. 2. Measure the in itial temperature R of the water in the beaker with a thermometer. Keep the thermometer in the beaker of water. 3. Add a heap of crushed ice at 0 C into the beaker of water. 4. Measure the final temperature of the water f when all the crushed ice has melted. 5. Calculate the change in temperature of water (R - f). 6. Measure the final volume of water Vf and calculate the volume of water formed from melted ice Vi by subtracting 100 cm3 from Vf. 7. The value of mass of melted ice mi is the same as Vi as 1 cm3 of water has a mass of 1 g. 8. Repeat steps 1 to 7 by increasing the number of heap of crushed ice by one heap each time such that there is a total of 6 sets of readings. Ensure that the temperature of crushed ice is at 0 C. 9. Tabulate the measured and calculated data as shown below. Vf / cm3 Vi / cm3 mi / g f / C (R - f) / C 10. Plot a graph of mi / g against (R - f) / C 11. Rearranging the equation, 336 𝑚𝑖 = 100𝑐𝑤(𝜃𝑅 − 𝜃𝑓) 𝑚𝑖 = 100336 𝑐𝑤(𝜃𝑅 − 𝜃𝑓) Calculate the gradient G of the graph. G = 100 336 𝑐𝑤 cW = 336 100 𝐺 The specific heat capacity of water cW is 3.36G. mi / g 0 (R - f) / C Alternatively, you can plot a graph of m / g against (R - f) / C Then 100𝑐𝑤(𝜃𝑅 − 𝜃𝑓) = 336 𝑚𝑖 (𝜃𝑅 − 𝜃𝑓) = 336100𝑐𝑤 𝑚𝑖 𝐺 = 336100𝑐𝑤 𝑐𝑤 = 336 100 𝐺

7 (c) When a filament light bulb is switched on, it radiates heat around and the temperature of the surrounding air increases. The relationship between the power supplied to a light bulb and the temperature of the surrounding air of the light bulb is thought to be T4 = k I + L where I is the current flowing through and T is the temperature of surrounding air (in Kelvin). k and L are constants. Suggest a plan to investigate the above relationship. Your plan should include: • the quantities that you will keep constant, • a suitable table in which to display your measurements and calculated values, • a statement of the graph that you would plot to test the relationship, • a sketch of the graph that you would obtain if the suggested relationship is correct. • an explanation of how you would determine k and L from your graph.

8 In this experiment, the independent variable is the current through the light bulb, and the dependent variable is the temperature of air. The controls in this experiment are the distance between the temperature sensor and the light bulb, and well as the e.m.f of the power supply. 1. Set up circuit (as shown in Fig 1) with light bulb connected in series with rheostat and ammeter. 2. Place a temperature sensor connected to a data logger placed at 5.0 cm away from the light bulb. 3. Close the switch. Measure and record the current through the bulb, I. 4. Measure and record the temperature of the air as T. 5. By varying the resistance of the rheos