#engineering

Shuttle Discovery flies near the ISS ‘posing’ for a series of inspection photos.

STS-121 - July 2006. ✨

Let’s ask a very generic question:

I hand you an object and ask you to predict whether the object would float or sink. How would you go about doing that ?

Well, you can measure the mass of the object and the volume of the object and can derive this quantity called Average Density

It is the average density of the entire object as a whole. If this object is submerged in a fluid of density , then we can draw the following force diagram:

Fun Experiment:

If you drop some raisins in soda, you will notice that they raise up and fall down like so (Try it out!):

                                                      Source

This is because air bubbles that form on the top of the raisin decrease its average density to the point that its able to make the raisin raise all the way from the bottom to the top.

BUT once it reaches the top all the air bubbles escape into  the atmosphere (its average density increases) and the raisin now falls down.  

Questions to ponder:

• Why do people not sink in the dead sea ?
• How are submarines/divers able to move up and down the ocean ? How would you extend the average density argument in this case.
• Why do air bubbles in soda always want to raise up ?
• If the total load that needs to on a ship is 25 tons. What should be the total volume of the ship in order to remain afloat if the density of sea water is 1029 kg/m3,

** This post is part of the ‘Flow series’ by FYPhysics and EcstasyShots!. Check out the previous posts here.

Recently we stumbled upon this cheap high voltage converter on Amazon which claims a boost from 3-6V to 400kV.

Although really skeptical about the 400kV claim, a lot of comments indicated that it did boost at the very least to 10kV so we got one of these to test it out.

    Schematic diagram for lighting up a CFL using the high voltage converter

                          Using a 1.5V battery to power the circuit

                              Using a 3V battery to power the circuit

And boom! There we go, that’s how you light up a CFL light bulb using a 3V battery!

If you do have access to a plasma globe or a tesla coil, things become a little bit more simpler:

                  Wireless (but not free) means to power a CFL light bulb

The way CFL light bulbs works is by exciting the electrons in the lamp and when they return to the ground state they radiate ultraviolet light. This emitted light is converted to visible light when it strikes the fluorescent coating on the glass.

So it really does not matter how you decide to excite the electrons to the higher energy state. It might be a high voltage converter, a tesla coil, a plasma globe, etc but all you need is a device that will kick those electrons inside the bulb from their ground state to the higher excite state. That’s all you need!

Have a great day!

Fluids

1. Buoyancy

   1. Origins of the Buoyant force
   2. How do hot air balloons work?
   3. Note on average density and how do ships not sink?

2. Flow Instabilities

   1. Plateau- Rayleigh Instability

3. Pilot Wave Hydrodynamics (completed with Nicole Sharp, FYFD)

   1. Introduction
   2. Chladni patterns
   3. Faraday instability
   4. Walking droplets
   5. Droplet lattices
   6. Quantum double-slit experiments
   7. Hydro single- and double-slit experiments
   8. Quantum tunneling
   9. Hydrodynamic tunneling
   10. De Broglie’s pilot-wave theory
   11. Resources and references on pilot wave hydrodynamics

4. Others

   1. How to photograph shock waves?
   2. Ultrasonically levitated water droplets
   3. Catching prey using vortices
   4. Whale Flukeprint
   5. Estimating the energy of an atomic bomb using dimensional analysis

Physics

1. Astronomy

   1. Measurements

      1. [How far away is the moon and lunar laser ranging experiment](https://fyphysica.tumblr.com/post/117782860366/how-far-is-the-moon)

      2. Parallax method, 61-Cygni and the Hipporcas mission
   2. How to use the hubble legacy archive (HLA) - 101
   3. The Chandler wobble
   4. On the orbital plane
   5. Supernova Sorcerer: Robert Evans
   6. A note on the Hydrogen spectrum
   7. On the strong 5577Å spectrum line
   8. Celestial wonders – Binary stars
   9. Dropping a feather on the moon
   10. Saturn’s hexagonal cloud pattern
   11. Beauty of eclipses on earth
   12. On disappearing shadows of Birds and airplanes

2. Classical Mechanics

   1. So. this is called blobbing
   2. The simple harmonic oscillator
   3. Using complex numbers in classical mechanics

   4. Remembering the Laplacian in different coordinate systems

      1. [Jackson's form of the laplacian in spherical coordinates](https://ecstasyshots.wordpress.com/2019/02/18/jacksons-laplacian-in-spherical-coordinates-proof/)

      2. Solving the Laplacian in spherical coordinates
   5. Euler-Lagrange equation for a classical field
   6. Cooking up a Lorentz invariant Lagrangian
   7. Length contraction , Time dilation and Lorentz Transformation: Pokemon edition

3. E&M

   1. Chocolate bar in Microwave(#1)
   2. Chocolate bar in Microwave(#2)
   3. On Diffraction and the Helical structure of DNA
   4. On Optical Tunneling and Evanescent waves
   5. Diamagnetic Levitation -Ig Nobel prize (2000)
   6. A note on levitating frogs and superconductivity
   7. Can you crush a soda can with lightning ?
   8. Pokemons and bioelectricity
   9. The holy grail of Electromagnetic Radiation
   10. Combinatorics and the two state paramagnet

4. Chaos

   1. Chemical Turbulence : Belousov Zhabotinsky reaction
   2. Dynamics of Love affairs: Valentine’s Day Gift Box

5. Quantum Mechanics

   1. Commutation relation in QM (using Index notation)
   2. A note on what makes solutions discretized?

Math

1. Feynman’s trick

   1. Intro to parametric integration
   2. Using Feynman’s trick on Laplace transform problems
   3. Feynman’s trick applied to Contour Integration

2. Differential equation

   1. Legendre Differential Equation (#1)
   2. Legendre Differential Equation (#2)
   3. Legendre Differential Equation (#3)
   4. Legendre Differential Equation (#4)

3. Beautiful proofs

   1. Divergence of the harmonic series
   2. Euler’s Sum
   3. Area under a sine curve
   4. When Gauss was a young child…

4. Number and Graph theory

   1. Homeomorphic Irreducible Trees with 10 vertices
   2. Divisibility tests
   3. Holy matrimony of Pascal and Sierpinski’s triangle
   4. Geometric series formula
   5. The tale of taylor series coefficients
   6. Division by 7

5. Pi-day

   1. How did the Greeks know that pi=3.14?

6. Others

   1. Why is (-1) x (-1) = +1 ?
   2. Why is 1+1 = 2 ?
   3. Only Time will tell - A Complex Number Tribute.
   4. Complex numbers are not complex
   5. Basis vectors are instructions
   6. The generalized product rule (Leibniz formula)
   [Finding n roots of unity](https://fyphysica.tumblr.com/post/176415634641/multiplication-and-n-roots-of-unity)

   8. [Never forget De Moivre’s formula](https://fyphysica.tumblr.com/post/176137661561/never-forget-de-moviers-formula-if-you-ever-find)

   9. Caustics
   10. Curves of constant width
   11. On the direction of the cross product
   12. The Knight’s tour
   13. The geometry of a pringle

Engineering

1. Themed adventures

   1. Up, up and away

      1. [The magnus effect](https://fyphysica.tumblr.com/post/134198455876)

      2. Introducing the wind-tunnel
      3. Flight dynamics : Pitch , roll and yaw
      4. Physics of “stall”
      5. On Taj Mahal and lift in airplanes
      6. Vortex Generators _( How inducing a vortex helps an aircraft )_
      7. Wingtip vortices ( The why and how about wing tip vortex )
      8. Have you heard about the popular y250 vortex on a F1 car? It’s amazing!
      9. Von Kármán vortex street
      10. Aerodynamic Flutter
      11. Landing on aircraft carriers

2. Train, Flights and cars

   1. Flight

      1. [What Is That Hole in the Tail of an Airplane?](https://fyphysica.tumblr.com/post/142619755241)

      2. Why do pilots use non polarized sunglasses ?
      3. Reverse Thrust
      4. Supersonic shock diamonds
      5. The radial engine
      6. Variable sweep aircrafts
      7. The Joukowski transform
      8. Vapor cones

   2. Rockets

      1. [ How to turn during flight ?](https://fyphysica.tumblr.com/post/132215818276/rockets-101-how-to-turn-during-flight-to-be)

      2. Why do shuttles orient belly up after a launch ?
      3. Spin stabilization
      4. How do you place a satellite in orbit?
   3. Pantograph and Trains
   4. This is a Dragster Blowover
   5. UV light, Thou shall not enter!

3. Technology

   1. The Touch Screen
   2. ‘Hook and Loop’: The fascinating tale of velcro
   3. That’s how a revolving fan works
   4. ABS - Anti-lock braking system
   5. Why are there rivets on your jeans?
   6. Making images from pixels

4. Others

   1. Walter lewin chalk trick | 1000 fps
   2. Why do shower curtains encroach your showering space ?
   3. Can dominos knock down the empire state building?
   4. Types of damping
   5. The Miura fold : Making flat surfaces smaller
   6. Powering a 13W CFL bulb using a 3V battery
   7. Square wheels on cars?
   8. De-constructing Backyard Brain’s TED talk
   9. Why can’t you cycle backwards?
   10. Baby powder and fire breathing
   11. Why do bullets spin when they leave the barrel ?
   12. Polish a surface well enough and you can turn it into a mirror !
   13. Small balloons exert higher pressure ?
   14. How does turning this knob control your fridge temperature?
   15. How does sand from Sahara end up in your windshield ?
   16. A note on Vibration and Washing Machines
   17. You cannot drown in Quick Sand!
   18. The great pyramid of Giza has 8 sides not 4!
   19. Why not just build a solar panel around the sun to solve all energy problems?
   20. Major types of engines - giffed