Science with dr. bob! - YouTube & Mansfield Cable Access TV

We're all scientists!

SwDB All Scientists screen capture

Science with Dr. Bob! - Season 1, Episode 1. - first aired 21 May 2018.

We're all scientists? Really?

Yes! At heart, we are all scientists. We can’t help it because we are human.


At its core, science is a system for asking and answering questions in a reliable way, and it follows a set of steps that humans naturally do. To demonstrate this principle, Dr. Bob does an experiment on a sugar-like substance, and in doing so, taps into the curiosity that drives science and demonstrates that science helps us understand the present and make predictions about the future.


“How does that work?” This key question is asked by children and adults alike; only the subject matter changes. Children wonder about their toys. Teenagers wonder about their peers. Adults wonder about their jobs. In each case, you wonder how something works, think up an idea that might be true, gather information that tests the idea, and if the new information doesn’t support the idea, you update the idea. In the end, our ideas are informed by the information – the evidence – we gather, and the best ideas are the ones supported by the most evidence. This is the process of science, and since we all do it every day, Dr. Bob argues we are all scientists. 


How does science help us? Science methodically tests our ideas about how the natural world works. Experiments in the present help us make predictions about how things might work in the future. Science follows the same steps we all use every day: Think of an idea you believe is true based on what you know – scientists call this idea a “hypothesis”. Gather information that tests the idea – scientists call this information “data” and they gather it through experimentation. Keep the idea or update it – scientists use data to support or refute a hypothesis. In this way, the best ideas about how things work rise to the top because they are supported by the best evidence. And by following these steps, we all follow the scientific method, and we are all scientists! 


Dr. Bob describes how he did the experiment on this episode here:

How to do the experiment:

The experiment on dissolving sugar was pretty straight-forward. 10 g of sugar plus 300 mls of water (about 1 1/4 cup), stir, and voila! Dissolved!


The unexpected results in today’s experiment came from crystals of sodium polyacrylate that I released from baby diapers. Unfortunately it takes a LOT of diapers to release just a LITTLE bit of crystals! I found it much easier to buy the crystals in bulk. Sodium polyacrylate is available from many online sources for about $20 per pound. Just search for “sodium polyacrylate absorbant polymer” online. 

 

The small volume demonstration I did involved adding drops of food coloring to 300 ml (1 1/4 cup) of water then pouring that water straight on top of 10 g (1/3 oz) of dry sodium polyacrylate. Distilled water worked best for me.


The large volume demonstration I did involved 10-times those amounts. I added 3 L (about a gallon) of distilled water straight on top of 100 g (about 4 oz) of dry sodium polyacrylate in a 4 L beaker. Because the sodium polyacrylate will absorb 200-300x its weight in water, you can use less of the crystals, but it will not solidify instantly. And the instant absorption is really cool to see! 

The Scientific Method

SwDB Scientific Method screenshot

Science with Dr. Bob! - Season 1, Episode 2. - first aired 20 July 2018.

Science Starts with Wonder!

What is the difference between the science we all do every day and the process of science carried out by professional scientists?  It's the formality of the steps.  We all follow the four core steps of the scientific method (which is why I believe we really are all scientists!) but professional scientists just do it more formally.

1. Wonder about something you see

We all start with wonder and curiosity. What is going on? Scientists call those things we see “observations” and we use our observations to ask a question about the natural world.

2. Think up an idea to explain what you see

Scientists call this idea a “hypothesis.”  An hypothesis is an educated guess about what is the correct answer to the question we asked in the last step. For a hypothesis to be scientific, it has to be testable.

3. Test that idea by getting more information

The tests we do are called  “experiments.” Scientists carefully design experiments that allows them to test the hypothesis they think is true. They take meticulous notes on how they did it, and this is called the “method” of the experiment. By carefully explaining their experimental method to others, they ensure the experiment is REPEATABLE, by them and by other scientists.

Scientists also take meticulous notes on what they observe from the experiment. The observations of experimental outcomes are called “results,” and usually, results are measurements, also called “data.” Again that is to make the experiment repeatable.

4. Decide what you believe

After observing lots of results, and analyzing them mathematically, scientists decide whether the data “supported” (that is, agreed with) or “refuted” (that is, disagreed with) the hypothesis. This decision is the “conclusion” that a scientist comes to. If the data support the hypothesis, you keep that hypothesis, if the data don’t agree, the data refute the hypothesis and you have to form a new hypothesis.

By following these four steps (and their sub-steps) strictly, science generates a predictable, repeatable, verifiable understanding of the world around us that is unmatched. 

How to do the experiment

The demonstration shown today requires a vacuum flask, a loud siren device that fits down into the flask, and a vacuum pump that can remove the air from the flask.  Be sure to use a vacuum container that you can open again after you pull the air out.  I put the rubber stopper on upside down so I could break the vacuum seal. Other vacuum containers have valves that are a bit easier to open reliably.

What is Sound?

Science with Dr. Bob! - Season 1, Episode 3. - first aired 20 July 2018.

Sound is waves of pressure moving through a material.

In this episode, I described and demonstrated what is sound, what is pitch, and what is loudness of sound.

How to do the experiment

This one was pretty simple, using a slinky to demonstrate compression waves and a speaker and sine wave generator to demonstrate the relationship of frequency and pitch.

Wind Instruments Everywhere!

Science with Dr. Bob! - Season 1, Episode 4. - first aired 13 Aug 2018.

Musical Instruments are EVERYWHERE

       We’ve talked about how sound is waves of pressure moving through a substance – air, water, or solid – but for today, let’s just talk about these waves in air. These pressure waves are like back-and-forth vibrations in the air. If you send those vibrations into the end of a hollow tube, the vibrations reflect back at you from the far end of the tube. Now, think what happens if you match the vibrations going into the tube with the vibrations reflecting back? The waves will actually add up with each other along the length of the tube to create what appear to be waves that stand in place – so called “standing waves” – where the going and coming waves add up with each other over and over!

       Wind instruments use all those facts to make notes. All wind instruments are hollow tubes containing air into which you introduce vibrations at one end either by splitting the air over the edge of a mouthpiece (as in a flute) or buzzing into the cup of a mouthpiece (as in a brass instrument) or buzzing with a reed mouthpiece (as in reed instruments). Those vibrations have a frequency that sets up standing waves in the instrument based on the length of the instrument. Keys help you to change the effective length of the tube and therefore change the length of the standing waves and therefore change the pitch (the note) you hear.

How to do the experiment

       You can turn any hollow tube into a wind instrument by buzzing into one end at a frequency that matches the natural vibration point (the resonance point) of that tube. Try buzzing into any (clean) tubes you find around the house to find the notes they make! You’ll have to press the tube around your lips quite firmly, then try buzzing with all different tightnesses of your lips to find the buzz that matches the tube. Try making a low buzz with very squishy lips to play long tubes like wrapping paper tubes; try a pretty high buzz with medium-tight lips to play medium tubes like paper towel tubes; and try a super high pitched buzz with super tight lips and lots of pressure to play toilet paper tubes. And as with any musical skill, practice makes perfect! Just be sure to stop before you drive your audience too crazy, and they’re sure to become big fans of your versatile musical talent!

Sound on Fire! (with a rubens tube)

Science with Dr. Bob! - Season 1, Episode 5. - first aired 20 Aug 2018.

A Rubens tube turns sound waves into flames!

       We’ve talked about how sound is waves of pressure moving through a substance – air, water, or solid – but for today, let’s just talk about these waves in air. These pressure waves are like back-and-forth vibrations in the air. If you send those vibrations into the end of a hollow tube, the vibrations reflect back at you from the far end of the tube. Now, think what happens if you match the vibrations going into the tube with the vibrations reflecting back? The waves will actually add up with each other along the length of the tube to create what appear to be waves that stand in place – so called “standing waves” – where the going and coming waves add up with each other over and over!

       In a hollow tube, those standing waves create points of calmness and points of peak change. We call the points of relative calmness “nodes,” and the air pressure does not change much at nodes. The standing waves also create points where the pressure is rising and falling very quickly. We call these points of big pressure change “anti-nodes,” and the air molecules in a tube at an anti-node are literally banging off the inside walls like crazy!

       So, with all those gas molecules banging against the sides of the tube at the antinodes, what if some of those gas molecules could escape, and what those gas molecules could burn? So was born the Rubens tube! Invented by German physicist Heinrich Rubens in 1905, the Rubens tube (or “standing wave flame tube” or just “flame tube”) shows the principles of standing waves in tubes in dramatic fashion! 

How the experiment is done

       After you get a Rubens tube, get a grown up. (This experiment requires a grown-up’s supervision!) Have the grown-up feed some propane into the tube and light it to get small consistent flames along the length of the tube. Now introduce some sound into the diaphragm end of the tube. When the pitch you’re sending in matches the natural resonance point (vibration point) of the tube, the waves will add up to create nodes with short flames and antinodes with tall flames!  Spectacular! Be sure not to try this experiment for too long because the tube gets HOT, and be sure to let the tube and all its attached parts cool before you touch them!