2 Sound
(4) a Zara and Sofia also listened to sound through a woollen hat. The loudness of the sound was 3.5 dB .
Draw another bar on the bar chart to show this.
b Is wool a solid, a liquid or a gas?
Solid
(5) Which kinds of materials on the bar chart do sounds travel through best?
Wood, Steel
Challenge
Zara and Sofia investigated how well sound travels through different materials.
They listened to the sound of a clock ticking through the materials to see how loud it was. These are their results:
\begin{tabular}{|l|c|l|}
\hline Material & Distance from clock in cm & Loudness of sound \\
\hline Plastic & 0 & \( \checkmark \checkmark \checkmark \checkmark \) \\
\hline Wood & 0 & \( \checkmark \checkmark \checkmark \checkmark \checkmark \) \\
\hline Water & 2 & \( \checkmark \) \\
\hline Air & 0 & \( \checkmark \) \\
\hline Cardboard & 5 & \( \checkmark \checkmark \) \\
\hline
\end{tabular}
(6) Identify the control, independent and dependent variables.
Control
Independent: The material Dependent: