# Ripple tank experiments

Ripple tanks are really cool ways to explore the way a wave behaves under the influence of a perturbation.

They are fairly simple to make, and are usually available in college and school laboratories to render better understanding of the wave phenomenon.

## How does it work ?

There is a usually an oscillating paddle( above– used to produce plane waves) or a point source/s ( below – used to produce circular waves ) which are actuated by eccentric motors, solenoids, etc + a shallow tank of water.

Here are some of my favorite renditions of physical phenomenon on a ripple tank. Check sources for more. Enjoy!

1. Diffraction

2.Double slit experiment

3. Reflection

4. Refraction

5. Parabolic Reflectors

A gif is worth a thousand pages. 😀

* Since the maximum gif size that one can upload on Tumblr is 2 Mb, the images had to be resized. The unedited album of gifs has been uploaded to Imgur (click here) if you are interested 😀

** Source videos : Educational Services Inc-1964  and Aerodynamic generation of sound

Next in this series : The beauty of interference.

Have a great day!

# Which would fall first in vacuum: A feather or a ball?

If you take a feather and a ball, and drop them simultaneously from your hand or from the top of a building what would you observe? Obviously the ball drops faster than the feather. But why?

Air resistance is the result of air molecules bombarding onto the object as it moves through the layer of air. The feather offers more air resistance and hence it falls slower.

Now you can up the ante and ask what if you remove the air resistance?

If you remove all the air molecules from the air,you would just get vacuum, a space devoid of any matter. With no molecules to bombard the object,

The feather and the ball would fall at the same rate as you can see in the animation. The demonstration was carried in the world’s biggest vacuum chamber.

( Extra: The same demonstration, but this time done on the moon :

Have a good day!

# Physics of the ballpoint pen

People often brag about Large Hadron Collider as having one of the most sophisticated Technology in the world. True, but even if you are living in France, it’s still inaccessible! I believe that accessibility is the true trait of technology.

Look around the place that you are sitting in. Do you see a Ball Point pen lying around in the vicinity? Chances are that it is, are really high. Today on FYP, we will unravel the modest physics that governs it.

## The physics.

Behold the ball in a ball point pen!.

To write you glide your pen onto the paper right? So what you are doing is rolling the ball that is present on the pen’s tip.

The ink flows continuously under the influence of gravity from the ink reservoir to the ball.

The ball rolls and the ink gets transferred onto the paper.

## How does the ink stay inside the pen?

Put a drinking straw into a glass of water (or any liquid) and then put your finger over the top end of the straw so it’s air tight. You can now lift the straw out and the liquid will not fall out of the straw!

Now switch characters and imagine the liquid to be the ink and the straw to be the ink reservoir and voila!

## Fun Fact.

Rollerball pen and Ballpoint pens work on the same principle. They differ in the type of ink used. While Ballpoint pens have a thicker oil based ink, the rollerball uses a liquid ink, thus giving its fluidity.

(Sources : http://home.howstuffworks.com/pen3.htm )

# Can dominos knock down the empire state building ?

## Chain Reaction.

Everyone knows that a line of standing dominos creates a fun chain reaction when you knock the first one over; but did you know you can use increasingly larger dominos and get the same result?

## The setup.

Professor Stephen Morris knocks over a 1-meter tall domino that weighs over 100 pounds by starting with a 5mm high by 1mm thick domino.He uses a size ratio of 1.5, meaning each domino is one and a half times larger than the last one. This is the generally accepted maximum ratio that dominos can have to successfully knock each other over.

Hans Van Leeuwen of Leiden University in the Netherlands, published a paper online showing that, theoretically, you could have a size ratio of up to two. But that’s in an ideal (and probably unrealistic) situation.

## Fun fact.

There are 13 dominoes in this sequence. If Professor Morris used 29 dominoes in total, with the next one always being 1.5x larger, the last domino would be the height of the Empire State Building.

Source: Physics Buzz.