You will investigate the time taken for water to flow through a small hole in the bottom of a can. You are provided with: • a clamp, boss and stand • a can with a small hole at the bottom • a supply of water in a 250 cm³ beaker labelled 'supply of water' • a 50 cm³ measuring cylinder • a 100 cm³ measuring cylinder • a funnel • a stopwatch • paper towels to mop up spillage. Some of the apparatus has been arranged for you as shown in Fig. 3.1. [Figure 3.1]

1. (a)(i)Use the 100 cm³ measuring cylinder to measure a volume V = 70 cm³ of water. Hold your finger under the hole at the bottom of the can. Pour the volume V of water into the can. Remove your finger and start the stopwatch immediately. Stop the stopwatch when the volume of water in the 50cm³ measuring cylinder is 30cm³. Put your finger back over the hole in the bottom of the can. Unclamp the can and empty the water remaining in it, and the water in the measuring cylinder, back into the beaker labelled 'supply of water'. The reading on the stopwatch is time t₁. Record t₁. t₁ = _______ s[1]
2. (a)(ii)Repeat (a)(i) one more time. Record the time as t₂. Find the average time tₐᵥ of t₁ and t₂. Give your answer to the nearest 0.1 s. t₂ = _______ s tₐᵥ = _______ s[2]
3. (a)(iii)The average flow rate R is given by: 30 cm³ R = _______ tₐᵥ Calculate R and give the unit of your answer. R = _______ unit _______[2]
4. (b)Repeat (a)(i) and (a)(ii) for values of V = 100 cm³, 90 cm³, 80 cm³, 60 cm³ and 50 cm³. Record all your results, including those you obtained for volume V = 70cm³ in (a)(i) and (a)(ii), in Table 3.1. Calculate tₐᵥ for each value of volume V and enter your answers into Table 3.1. Complete Table 3.1 by writing appropriate headings, with units, in the top row. [Table 3.1][3]
5. (c)On the grid provided in Fig. 3.2, 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. [Figure 3.2][4]
6. (d)Suggest why values of 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]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.