Gravitational Waves: Modelling Rotating Black Holes

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Background Information: 

Brief Description: Detectable Gravitational Waves can be created by massive compact objects (like black holes or neutron stars) that orbit each other. How can we model this with everyday materials? How can we use Tracker to carry out digital video analysis of our model to study the circular motion?

How does the lesson relate to STEAM education: This activity focuses on science, making use of a physical model of orbiting spheres, with digital video analysis to study the circular motion. Physics concepts of circular motion, speed and period are central to this activity. Students will be collecting data and using plots of their data to describe the motion of the spheres.

An additional optional focus on Engineering is given, if students want to create their own models and film them to analyse and collect data using Tracker.  Mathematical skills are applied extensively with data analysis and graphing.

Age Range: 12-16 (non-mathematical treatment), 16+ (using tracker software)

Didactical Hours: 50 min up to 2 didactical hours (with extension activities)

Learning objectives: The students will:

- compare and evaluate physical models to the cosmic events
- use mathematical reasoning to justify experimental design and data collection
- correctly use the term period when describing circular motion

Relation to the Big Ideas of Science:

Energy > Forms, Conservation of energy and energy transfer > Conservation and degradation of energy: When massive compact objects orbit each other, they lose energy as gravitational waves. The first evidence of gravitational waves came in 1974 from a system of neutron stars and how they were losing energy.

Energy > Forms, Conservation of energy and energy transfer > Energy and mechanical waves: Gravitational waves are very hard to detect because they have a tiny effect. Other sources of vibrations can affect the detectors and mask the signal.

Forces > Types of interactions > Gravitation and its effects: When two compact objects orbit each other, they radiate gravitational waves.

Forces > Types of interactions > Gravitation and its effects: Gravitational waves are more easily detected from rotating systems of massive compact bodies. The first evidence came in 1974 from a rotating system of neutron stars.

Universe > Earth's place in the universe, Celestial objects > Stars, their life and death: Gravitational Waves are strongest (and more easily detectable) from extreme systems. These include stars at the end of their lives like neutron stars and black holes.


The Polar Star consortium is grateful for the input of the Star Advisors, who helped to choose the star topics. We would like to warmly thank Star Advisors, who provided valuable ideas and materials for this particular activity:  Christian Collette, Maria Eleftheriou and Paula Galvin.

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POLAR STAR aims to bring together state-of-the-art learning pedagogies and combine them with exciting activities that focus on contemporary science, thus helping teachers to introduce STEAM successfully in their class. At the same time the project will focus on the development of students’ key skills and competences as well as deepening their knowledge of fundamental science principles, increasing their appreciation of science and technology and their role in todays’ societies. POLAR STAR aims to offer an open and innovative training framework to teachers of primary and secondary education which will focus on:

  • Promoting the 'Science as a Whole' concept;
  • Promoting a holistic STEM educational approach;
  • Promote the introduction of contemporary science activities in schools;



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