Phys Lab

Physics Laboratory

Browser Oscillation Lab

Measure rope and spring oscillations in a clear, guided workflow.

Phys Lab helps students run rope-pendulum and spring-pendulum experiments with a webcam, one red marker, and guided investigation modes.

Choose an experiment, enter the required setup values, align the camera, record a run, review the measured frequency, and save only the runs you trust.

Open Live Lab Read Setup Guide

What You Need

Simple Classroom Setup

Use a desktop or laptop browser, a webcam, one pendulum bob with a red marker, and a quiet background with steady lighting.

What You Measure

Frequency From Motion

The live view shows a provisional reading during capture, then the stopped run is reviewed and reduced to a final frequency before saving.

Investigation Modes

Three Standard Questions

Test mass independence for the rope pendulum, the rope length law, or the spring-mass frequency law while the app reminds you which setup variable should stay fixed.

Overview

What this lab does for a new user

The page is organized around the same sequence you follow in class: prepare the setup, capture motion, review the result, and compare saved runs.

Core Task

Capture One Clean Run At A Time

  • Use the webcam to track the pendulum bob through its red marker
  • Start and stop each run manually so the capture matches the release
  • Review the result before adding it to the current session

Before You Record

Set Up The Camera And Pendulum Carefully

  • Small-angle simple-pendulum motion in one plane
  • Camera placed perpendicular to the swing plane
  • One clearly visible red marker and a stable background

Choose The Right Mode

Choose Rope Or Spring Motion

  • Mass Independence: hold length fixed, vary mass
  • Length Law: hold mass fixed, vary length
  • Spring Pendulum: keep the spring fixed, vary mass, and measure vertical motion
  • App warns when the controlled setup parameter drifts across runs

Live Lab

Record, review, and compare one run at a time

The workspace below follows the normal lab order: choose the investigation, enter the setup values, enable the camera, capture the motion, review the final measurement, then save the run for comparison.

Experiment Mode

Choose the investigation

Persisted locally

Mass Independence

Hold pendulum length fixed, vary bob mass, and compare the saved frequencies.

Controlled Variable

Length

What Changes

Mass

Session warnings will fire if saved runs in this mode use inconsistent lengths.

Draft changes save locally as you edit.

Camera Stage

Live tracking and provisional measurement

Camera preview

Red-marker tracking view

Enable the webcam, place the red pendulum marker in frame, and align the motion to move mostly left-to-right on screen. The overlay will mark the detected bob and the current horizontal analysis axis.

Run State

Camera off

Marker

Waiting for preview

Horizontal Axis

No signal

Live Frequency

Awaiting run

  • Use a desktop or laptop browser
  • Camera should be perpendicular to the motion plane
  • Use one approved red marker and a quiet background
  • Keep the swing mostly horizontal in the camera frame

Current Capture

Live signal and stopped-run summary

Review before save

Current Mode

Mass Independence

Draft Mass

Not set

Draft Length

Not set

Stopped Run Estimate

Awaiting captured run

Run Duration

0.0 s

Valid Samples

0

Tracking Quality

No capture yet

Start a run to capture the horizontal marker signal. The live estimate is provisional during capture, then the stopped run is re-evaluated with Prony analysis before it can be saved.

Primary Prony Mode

Awaiting stopped run

Stop a run to prepare the signal, fit Prony modes, and select the strongest stable candidate as the final frequency estimate.

Review Decision

No run pending

Stopped runs stay in review until you either keep them in the current session or discard them.

Rank Frequency Period Amplitude Damping Status
No Prony candidates yet.

Session State

Saved runs and active-mode comparison

Stored Modes

2

Current Draft

0 / 2 fields

Saved Runs

0

Active Mode

0 runs

Save reviewed runs to compare frequency against the varying setup variable in the current experiment mode.

Run Time Mass Length Frequency Quality Action

Lab Manual

Experiment manual with theory, setup, and expected results

Six classroom investigations connect the live measurement tool to the oscillator models. Current app modes are marked as live; planned spring extensions are documented first so the theory is ready before the controls expand.

Shared Setup

Camera, marker, and motion limits

  • Use one red marker on the bob, hanger, or moving mass.
  • Place the camera perpendicular to the motion plane.
  • Keep pendulum angles small and spring stretches moderate.
  • Capture several oscillations, then keep only reviewed runs.

Core Models

Two oscillator laws

f = 1 2π √ g / l
f = 1 2π √ k / m

Current App Mode

Rope Pendulum: Mass Independence

Keep the pendulum length fixed, change bob mass, and test whether measured frequency stays approximately constant.

ω = √ g / l
f is independent of m
Controlled
Length l
Varied
Mass m
Expected
Flat frequency versus mass
  1. Measure length from pivot to bob center.
  2. Record runs with several bob masses.
  3. Reject runs with marker loss or changed length.
  4. Compare saved final frequencies.
Mass (g)Length (m)Frequency (Hz)
500.750
1000.750
1500.750
l fixed track x
Keep length fixed while changing the bob mass.
mass f
Expected trend: frequency stays nearly flat.

Current App Mode

Rope Pendulum: Length Law

Keep mass fixed, vary pendulum length, and show that longer pendulums oscillate more slowly.

f = 12π √ g / l
f ∝ 1√l
Controlled
Mass m
Varied
Length l
Expected
Frequency decreases with length
  1. Use one bob for all runs.
  2. Measure length from pivot to bob center.
  3. Capture runs at several lengths.
  4. Compare f against 1 / sqrt(l).
Length (m)1/sqrt(l)Frequency (Hz)
0.400
0.600
0.800
short long
Only length changes; mass stays fixed.
length f
Expected trend: longer length lowers frequency.

Current App Mode

Spring Pendulum: Mass Dependence

Use the same spring, change attached mass, and measure how vertical oscillation frequency changes.

ω = √ k / m
f ∝ 1√m
Controlled
Spring constant k
Varied
Mass m
Expected
Heavier masses oscillate slower
  1. Use one spring for all runs.
  2. Keep motion vertical and avoid sideways swing.
  3. Capture runs with several masses.
  4. Convert grams to kilograms for theory checks.
Mass (g)k (N/m)Frequency (Hz)
505.0
1005.0
1505.0
track y
The marker should move mostly up and down.
mass f
Expected trend: heavier mass lowers frequency.

Documentation First

Measuring Spring Constant

Estimate spring stiffness from static extension before using k in dynamic oscillation predictions.

F=mg
F=kx
k=mgx
Controlled
Spring
Varied
Hanging mass
Expected
Force is linear with extension
  1. Measure the unloaded spring length.
  2. Hang known masses one at a time.
  3. Record extension after motion stops.
  4. Estimate k from the slope of force versus extension.
Mass (kg)Force (N)Extension (m)k (N/m)
0.050
0.100
0.150
x ruler
Measure extension from the unloaded length.
extension F
Expected trend: slope gives k.

Documentation First

Springs In Parallel

Mount two springs side by side so their forces add at the same extension.

k* = k1 + k2
Controlled
Mass
Varied
Spring arrangement
Expected
Combined spring is stiffer
  1. Measure or identify k1 and k2.
  2. Mount both springs to one hanger.
  3. Keep the hanger level.
  4. Compare measured stiffness with k1 + k2.
k1k2Predicted k*Measured k*
Parallel springs share extension and add forces.
extension F
Expected trend: steeper force-extension line.

Documentation First

Springs In Series

Connect two springs end to end so the same force stretches both and extensions add.

1k* = 1k1 + 1k2
Controlled
Mass
Varied
Spring arrangement
Expected
Combined spring is softer
  1. Measure or identify k1 and k2.
  2. Connect the springs end to end.
  3. Attach the mass to the lower spring.
  4. Compare measured stiffness with the series prediction.
k1k2Predicted k*Measured k*
Series springs share force and add extensions.
extension F
Expected trend: shallower force-extension line.

Quick Start

How to run your first session

Follow these four steps in order when you open the lab for the first time.

Step 1

Prepare The Apparatus

Attach the red marker, position the camera perpendicular to the motion, keep the background calm, and start either a small rope swing or a small vertical spring oscillation.

Step 2

Choose A Mode And Enter Values

Select Mass Independence, Length Law, or Spring Pendulum, then enter the current mass and the required setup parameter before you start the run.

Step 3

Capture And Review The Run

Enable the camera, start the run, stop it after several oscillations, and inspect the final measured frequency before deciding whether to keep it.

Step 4

Save And Compare

Save accepted runs into the current mode, compare them on the chart, and export the session if you need to keep the data outside the browser.