Broadrick Prelim P3 Ans

2024 4E Prelim Paper 3 Practical Test Marking Scheme Question 1 (a) l = 2.1 cm d = 1.6 cm [1] [1] (b) m = 5.3 g n = 30 N = 34 [1] [1] (c) D = 0.0700 cm [1] (d)(i) (d)(ii) (d)(iii) L = 171 cm V = 0.658 cm3 ρ = 8.06 g / cm3 [1] [1] [1] (e) Source of error: 1. Precision of the ruler is only 0.1 cm 2. There is a portion of wire between the coiled part and the 2 turns on each end that is not accounted for. Effect on calculated value of ρ: 1. Value of V is overestimated, so calculated value of ρ may be smaller than the actual value of ρ. 2. Value of V is underestimated, so calculated value of ρ may be larger than the actual value of ρ. [1] [1] Total marks: 10 Question 2 (a) θ = (results to be updated on practical dry run) [1] (b) r = (results to be updated on practical dry run) [1] (c) T = (results to be updated on practical dry run) [1] (d) Planning mark allocation: Variables – 1m, 1m Performing experiments (starting value of independent variable, measuring dependent variable & 5 more values to obtain more readings, table) – 1m, 1m Statements and sketch of graphs – 1m, 1m How to achieve accurate results – 1m [7]

Plan 1 Independent variable: distance that the piece of Blu-Tack moves d Dependent variable: time taken for the piece of Blu-Tack to reach the bottom of the cylinder T Control variable: type of oil, radius of the piece of Blu-Tack r. 1. Fill the measuring cylinder such that the height of the column of oil is 5 cm so that the distance that the piece of Blu-Tack moves is d = 5 cm. 2. Place the piece of Blu-Tack at the top of the oil as shown in Fig. 2.1. Use the string to hold the piece of Blu-Tack so that it just touches the surface of the oil in the measuring cylinder. Release the string and start the stop-watch. Stop the stopwatch when the piece of Blu-Tack reaches the bottom of the measuring cylinder. Record the time T1 taken for the piece of Blu-Tack to reach the bottom of the cylinder. 3. Repeat step 2 two more times to obtain T2 and T3 and find the average value Tavg to achieve accurate results. 4. Repeat steps 1 – 3 for five further values of d (8 cm, 10 cm, 12 cm, 15 cm, 18 cm). 5. Record the values of d, T1, T2, T3, and Tavg in a table. 6. Plot the graph of Tavg against d. If the suggested relationship is correct, we will obtain the following graph: The graph should be a straight line passing through the origin if T is directly proportional to d. [1] [1] [1] [1] T / s d/ cm 0

Plan 2 Independent variable: radius of the piece of Blu-Tack r Dependent variable: time taken for the piece of Blu-Tack to reach the bottom of the cylinder T Control variable: type of oil, distance that the piece of Blu-Tack mov