Suggest why she puts the coins at the centre of the card.
Describe how the student uses this balance to determine the mass of a coin to the nearest $0.1\,\text{g}$.
Each coin has a mass of $3.4\,\text{g}$. The required number of coins is 16, 15, 16, 14, 15. Find the average mass $m$ in grams that the card can support. Give your answer to 2 significant figures.
Suggest one way in which her method makes a fair comparison possible.
Enter your value of $m$ for $w = 12\,\text{cm}$ from 1(b)(ii) in Table 1.1. On Fig. 1.2, draw a graph of $m$ on the $y$-axis against $w$ on the $x$-axis. Start both axes at the origin. Sketch the smooth curve of best fit.
Extend your curve to estimate the mass of coins that collapse the bridge for a card that is $13\,\text{cm}$ wide. Show your working on the grid in Fig. 1.2.
Suggest how the student can alter the apparatus so that the bridge supports more mass for all widths of card.
Each student in the class has only one piece of card at the start of the experiment. A second student chooses to carry out the experiment beginning with a $2\,\text{cm}$ wide piece of card and then increasing the width. Suggest why this creates a problem.