Question

In a device called the ballistic pendulum, a compressed spring is used to launch a steel ball horizontally into a soft target hanging from a string. The ball embeds in the target and the two swing together from the string. Describe the energy transfers and/or transformations that take place during the use of the ballistic pendulum and at what points they occur.

Answer 1

Initially the spring is compressed to a distance, and the work done in doing so is stored as the potential energy of the spring.

When the spring is released, the mass moves forward and when the mass is released from the spring, the potential energy of the spring gets converted into the kinetic energy of the mass. ( At ideal situation when there is no frictional losses. )

Now the mass moves with constant velocity to hit the target. The collision is completely in elastic.

Means momentum is conserved but kinetic energy is not conserved.

Now the target and mass moves together with a velocity.

The swing together to a maximum height above the ground level converting kinetic energy into potential energy.

So in total two energy transformations occur.