Newton’s Cradle is a device that is used in teaching to demonstrate the physical laws of conservation of energy and momentum. The device consists on a series of spheres suspended from wires. The spheres are pulled and released, and then collide with each other. But there must be something charming about Newton’s Cradle which has made it transcend the classroom, as it is used is also used for entertainment, or as a decorative toy, and has even been featured in movies. When the moving ball collides with the stationary balls, the force is transmitted through the stationary balls to the ball on the far side. Depending on the number of moving balls and stationary balls as well as their location and the timing of release of the balls, several recurring collision patterns can be generated as shown in the video below.
If you have the time, there is even a computer simulation of Newton’s Cradle that you can operate without having to deal with the effects of friction which eventually dampen the performance of the real device.
The domino tumble is a great example of the conversion of potential energy into kinetic energy (energy of movement) and the internet is filled with videos of elaborate domino tumbles involving thousands of dominoes such as the one below.
Less well known variants of the domino tumble are the double domino and domino amplification effects.
The double domino effect occurs when the regular forward wave of toppling dominoes is followed by a second wave in the opposite direction. This occurs because the first wave leaves the dominoes lying partly on top of each other with some of their potential energy still intact. When the terminal domino falls to the ground, it fails to provide the support needed for the domino immediately before it which falls to the ground too followed by the next one and so on. The process and the math involved are explained in the video below by Matt Parker from standupmaths.
The domino amplification effect is a far more interesting for me because with a tiny input energy you can release a huge amount of energy in a process that is somewhat similar to a chain reaction. This is possible because a domino can topple over another domino that is 1.5 times larger. Thus by placing dominoes of increasing size one after the other you can topple a gigantic domino using a much smaller one achieving amplifications factors in the billions. The process and the physics involved are explained in the video below.
The domino amplification effect was featured in an episode of Mythbusters shown in the video below.
One of my Twitter followers named Ken has a You Tube Channel called Kid’s Fun Science where he posts the science experiments that he conducts during Science Night at his local Elementary School. In the video below he shows the blowing up of a watermelon employing rubber bands using the potential energy accumulated in rubber bands after stretching them around the melon.
There are several forms of potential energy. The potential energy stored in an stretched rubber band is called elastic potential energy. This type of potential energy can be stored in elastic materials as a result of stretching or compressing and can be converted very rapidly into kinetic energy (energy of movement) when the force opposing the compression or stretching (in this case the structural integrity of the watermelon) is eliminated. Check out at the end of the video the final fate of the rubber bands after the release of their pent-up energy!
I encourage you to check other fun science experiments in the Kid's Fun Science You Tube Channel and to follow them on Twitter, Facebook, Instagram, and Pinterest.