Investigation question

Do we need air to hear sound?

Use a sealed cabinet, a vacuum bell jar, and several material paths to determine what a sound signal needs to reach a detector.

Notebook 8.2 · Entry 7 Experiments on Sound Source · Path · Detector

ACOUSTIC LABORATORY · NOTEBOOK ENTRY 7

Begin with the sealed cabinet.

A buzzer will ring inside a cabinet that is sealed and resting on a balance. A sound detector waits outside. Air cannot leave this closed system, but the cabinet and the surrounding air still provide a material path.

First write what you expect the detector to show. Then use three experiments to test whether air specifically is required.

Investigator’s name Class or period

Date entered—Your work remains in this browser.

Notebook rule: predict before testing. These experiments show effects we can measure. They do not yet reveal the tiny mechanism inside matter.

Entry before evidence

What will the detector show?

Starting system: A buzzer and air are sealed inside a cabinet on a balance. The detector is outside. Air cannot leave the cabinet.

When the buzzer rings, choose the prediction that best matches your current thinking. No signal.Air must leave the source for sound to reach the detector. The detector will register a signal.Sound can pass through material even while the air stays sealed inside. The detector will register a signal.Sound can travel even where no material path is present.

What makes you think the detector will—or will not—respond?

Choose a prediction and explain your thinking.

The acoustic laboratory

Choose an experiment table

Move through the room in any order. Select a table to examine its apparatus and record evidence.

Three stations

Three experiment tables in a Victorian laboratory: a sealed cabinet, a bell jar and pump, and a gong

Required comparisons0 of 7 completed

Compare the cabinet with its lid open and sealed.

Experiment I

The Sealed Cabinet

Can sound reach a detector even when air cannot leave the source?

Closed system

Prepare the system

Start with the lid open. Ring the buzzer, record it, then seal the lid and compare the sound and mass.

MASS1248.6 g

LID OPEN

DETECTORReady

Latest observation

The apparatus is ready.

Condition: —
Detector: —
Other measure: —

What did you observe?

Choose a condition and run an experiment.

The society’s record

Evidence ledger

Compare what was changed, what stayed inside the system, and what the detector registered.

No.	Experiment	Condition	Detector	Measure	Observation	Actions
No evidence entered yet.

Final entry

Claim · Evidence · Reasoning

Use observations from more than one experiment to answer the question below.

DRAFT

Question to answerDo we need air to hear sound?

Decide whether sound needs air specifically, another kind of material, or no material at all to travel from a source to a detector.

CClaimDirectly answer: Do we need air to hear sound?

Build your evidence from the data table.

Select the specific trials and measurements you want to use. The notebook will insert the data, but you must explain what it means.

Student-selected data

Choose the observations to include

Select	Experiment	Condition	Detector	Measurement	Your observation
Record trials to build this table.

0 observations selected

EEvidenceUse at least two specific observations. RReasoningExplain why the evidence supports your claim.