Physics 9702/31 — May/June 2021

● Use the adhesive putty to attach the $100\text{ g}$ mass to the metre rule as close as possible to the $80\text{ cm}$ mark, as shown in Fig. 1.1.

● The distance between the $50\text{ cm}$ mark and the centre of the mass is $L$.

Measure and record $L$.

$L$ = ______

● Set up the apparatus as shown in Fig. 1.2.

● Suspend the rule from the long string loop at the $50\text{ cm}$ mark on the rule.

● Add the two $50\text{ g}$ masses to the mass hanger to make a total mass $m$ of $110\text{ g}$. Suspend mass $m$ from the spring.

● Record $m$.

$m$ = ______ $\text{g}$

● The distance between the string loop supporting the spring and the $50\text{ cm}$ mark on the rule is $b$.

The distance between the top of the top loop of the spring and the bottom of the bottom loop of the spring is $x$, as shown in Fig. 1.2.

Adjust the position of the string loop supporting the spring until the rule is horizontal and in equilibrium.

● Measure and record $x$ and $b$.

$x$ = ______
$b$ = ______

Repeat (b) with different values of $m$ until you have six sets of readings. Record $m$, $x$ and $b$. Include your values from (b).

Record your results in a table. Include values of $\frac{1}{b}$ in your table.

It is suggested that the quantities $b$ and $x$ are related by the equation

$$\frac{1}{b} = Px + Q$$

where $P$ and $Q$ are constants.

Using your answers in (d)(iii), determine values for $P$ and $Q$. Give appropriate units.

$P$ = ______
$Q$ = ______

A student repeats the experiment placing the $100\text{ g}$ mass closer to the $50\text{ cm}$ mark on the rule.

Theory suggests that $P$ and $Q$ are both inversely proportional to $L$.

For this experiment, draw a second line on the graph to show the expected results. Label this line W.