A student investigates the time taken for water to flow through a small hole in the bottom of a can. The apparatus is arranged as shown in Fig. 3.1.

1. (a)(i)The student: • uses the 100 cm³ measuring cylinder to measure a volume V = 70 cm³ of water • places a finger under the hole at the bottom of the can and pours the water into the can from the measuring cylinder • removes the finger and, at the same time, starts the stopwatch • records the time t₁ when the volume of water collected in the measuring cylinder is 30 cm³ • stops the stopwatch. Fig. 3.2 shows the reading on the stopwatch at time t₁. Record t₁. t₁ =[1]
2. (a)(ii)The student repeats (a)(i) and records the time t₂ shown in Fig. 3.3. Record t2 and find the average time tav of t₁ and t2. Give your answer to the nearest 0.1 s. t₂ = tav =[2]
3. (a)(iii)The average rate of flow R is given by: R = 30 cm³ / tav Calculate R and give the unit of your answer. R =[2]
4. (b)The student repeats (a)(i) and (a)(ii) for values of V = 100cm³, 90 cm³, 80 cm³, 60 cm³ and 50 cm³. The volume of water collected in the measuring cylinder underneath the can is 30 cm³ for each value of V. The readings are shown in Table 3.1. In Table 3.1: • complete the headings, with units, in the top row of the table • add your readings from (a)(i) and (a)(ii) • calculate the average time for each set of readings. Table 3.1 V 100 16.0 16.2 90 16.9 17.4 80 18.9 19.7 70 60 25.3 25.9 50 31.1 31.3 [3]
5. (c)On the grid provided in Fig. 3.4, plot a graph of tav on the y-axis against V on the x-axis. You do not need to start your axes at (0,0). Draw the curve of best fit.[4]
6. (d)Suggest why times t₁ and t₂ for values of V below 50 cm³ are not measured.[1]
7. (e)On your graph, sketch the line you would expect to see if the small hole in the can is made slightly bigger. Label this line L.[1]

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