Conservation of Energy using an Airtrack E-practical

A realistic 3D virtual physics experiment

Confirmation of the conservation of energy using an airtrack by setting timer gates and glider positions, and recording the times through the gates. Control the air-pump to create a near frictionless track - just as you would in the laboratory.

Realistic experimental technique

E-practicals are 3d, highly realistic emulations based on a blend of theory and the actual practicals, giving an authentic experience of doing the actual practical in a laboratory. Students operate the apparatus, make measurements and obtain their own results. It is designed to reproduce the experience of performing the practical rather than simply demonstrating the underlying physics. Like a real experiment, it can be done badly. Careless setup or measurements can produce poor results, so students have to apply experimental technique and take care with their measurements.

Useful when laboratory access is limited

Ideal for preparation before a practical, revision afterwards, missed practicals, home study, or demonstrating an experiment when setting up the real apparatus isn't practical.

Works directly in a browser

No installation is required. Windows, Mac and suitable mobile devices can run the WebGL e-practical.

Watch it in action

This shows how the e-practical can be used. In particular it shows how the student or teacher interacts with the apparatus and how the interaction can be controlled using the mouse or the alternative on-screen controls.

What you get

The application is supplied as a PowerPoint which provides background, a synopsis of what the student will learn, a description of the Physics involved, a description of the apparatus, the independent and dependent variables, the method, a link to the interactive online e-practical, analysis of the results and further discussion.

School/Department licence £9.99

Valid for 1 year

Introduction

In this e-practical you use a rifle to shoot a bullet at a suspended block of wood. The bullet buries itself into the wood inelastically and transfers its energy to the block, some of the energy is used up as noise, heat, and the effort needed to burrow into the wood. The block then moves sideways and upwards converting its kinetic energy into potential energy. The height that the block rises indicates the amount of potential energy that the block and bullet combination gain. This can be equated to the kinetic energy of the block and bullet combination at the point when the bullet buries itself in the wood and the two start moving. This allows us to calculate the momentum of the block and bullet at this time, which due to the law of conservation of momentum must be equal to the momentum of the projectile before it strikes the block.

What students do

Record the at rest position on the horizontal scale. Note this initial position and then fire the gun by clicking on the trigger. Note the furthest point of the blocks swing. You may have to repeat this several times to get an accurate reading. Note: you can zoom in and out using plus and minus on the keyboard.
Once you have the reading for the position of the furthest point reached you can then calculate the horizontal distance moved by the block by subtracting the at-rest position.
The length of the rope is 1.5m. The mass of the wooden block, Mb is 2kg and the mass of the shell, Ms = is 0.01075 kg.
Use the formulae in the Physics section to first calculate the potential energy gained by the block and hence the velocity of the block just after impact.
The final equation in the Physics section can then be used to calculate the velocity of the shell.

Want to experience an e-practical yourself?

Try our free Magnetic Field for a Coil e-practical.

Other Physics E-Practicals

Explore the other e-practicals available at GCSE, A'level and Undergraduate

This section is adapted from material developed by Dr Robert Lucas and is related to the book High School and Undergraduate Physics Practicals, published by CRC Press.