QUEST teamed up with us to show you how to make a tabletop linear accelerator that demonstrates the finer points of kinetic energy by shooting a steel ball.

## 2 thoughts on “MAKE it at Home: Table-top linear accelerator”

1. MakeFan says:

The whole point of doing experiments like this is to explain and then demonstrate a certain concept. If you do an experiment and don’t really explain what is going on, then what was the point?

Here is a short explanation of what’s going on:

When he releases the first ball it accelerates to the first magnet. It hits the first magnet and transfers it’s energy to the ball attached to the other side. Notice that there are 2 balls on the right side of each magnet. The reason for this is to launch the launched ball away from the launching magnet and it’s magnetic field as much as possible. The 2nd ball is launched by the 1st balls energy, and heads toward the 2nd magnet. At this point the 1st magnet is trying to decelerate the ball back, and the 2nd magnet trying to accelerate the ball forward. But since the 1st magnet is farther away (remember the extra ball on the right) than the 2nd magnet accelerating it, the ball accelerates or gains energy with each launch.

In the end, the last ball has greater energy that the energy put into it by the first ball. This is the result of all the accelerations provided by the target magnet, minus the deceleration of the launching magnet, minus any losses due to friction and energy transfer between the balls hitting the magnet and launching the ball on the other side.

If the energy of the last ball is greater than the energy put in by the first ball, where is this extra energy coming from? (exercise to the reader)