What you need:
A long, long string of beads
A large transparent container
What to do:
1. First you need to load the string of beads into the container in a way that it doesn’t tangle. This requires patience and practice. First, you lay one end of the string at the base of the container. Then you lay the beads in a circular layer one over the other.
2. Once the beads are loaded, hold the container high in the air with one hand. With the other hand, take the end of the string at the top of the bead-pile and quickly toss it over the edge of the container towards a table or the floor. This motion needs to be a fast tug.
What happens:
The entire string of beads falls like a fountain over the container. In some cases, especially metal beads, you see the beads arcing high above the mouth of the container while cascading down.
If you want to practise some neat skills, you can try tossing these beads from one container to another too.
Why?
The first principle behind the motion of the beads is inertia. According to one of Newton’s laws of motion, inertia is the tendency of a motionless object to remain at rest or of a moving object to stay in motion until an external force acts on them. Thus, when you tug on the string of beads, you apply a force that puts the strand in motion and it continues to tumble out of the container like a waterfall.
The second principle is related to energy. When you raise any object above the ground, you give it gravitational potential energy’ which is nothing but the energy that the object holds due to its position. This energy increases as the height of the object from the ground increases. So, the higher up you hold the beads, the more potential energy they gain.
It is the law of the world that energy cannot be created or destroyed; it can only change form. So when you tug the beads, you convert the potential energy in the beads to kinetic energy’. Kinetic energy is the energy that a body has due to motion. The faster an object moves, the more kinetic energy it has.
Sometimes, the beads arc above the mouth of the container. This happens because according to inertia, the beads want to keep moving upwards (because that’s the direction of the tugging force you had applied) and out of the container. But gravity wants to pull the beads down to the ground. Gravity wins and the strand of beads changes its direction and loops downwards. Also, since the strand of beads is not very flexible, it needs to loop to change direction which gives us that spectacular arc.
Picture Credit : Google
