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Density Required Practical, Accuracy and Precision (Two Dense Objects)

Photograph: Jane Ni (see below for link)

Summary

Thomas and Robin chat about another required practical in UK GCSEs, measuring the density of regular and irregular objects. They run down the rabbit hole of accuracy vs precision before chatting about crazy ways of measuring everyday values.

Photograph: NSO/AURA/NSF

Physics in the news this week is the recent close up photograph of the surface of the Sun, or “golden nuggets” as Thomas called it. Each pixel is 30km, meaning that if this were the whole sun the photo would be metres across.

The next topic is the everyday required practical in the UK of measuring density. What are the pitfalls? Who doesn’t love a Eureka can? It turns out that Robin is not a fan, and Thomas finds them a tricky proposition too.

A quick foray in to Accuracy vs Precision where Thomas reminisces about WWI (he’s not that old) and tells a story from his past to illustrate the difference.

The final part of the podcast has Thomas telling Robin about how he measured the diameter of ball bearings by dropping them in glycerol as an analogue for the Millikan experiment.

Links

Join in!

Please share ideas or successes – or indeed questions – on our Facebook Page: https://fb.me/physicstp .  You can also message us via our website contact form at the.physicsteachingpodcast.com, Twitter @physicstp, email using  the address given in the podcast (if we remember) or by leaving a voice memo using WhatsApp or Telegram to the phone number in our Twitter profile, +44 7898 814716 (don’t call the number, nobody will answer, just hold down the microphone icon and speak your message or upload an mp3 or ogg). Don’t forget to tell us your name because we may use your audio in a future episode.

The music we use remains One legged equilibrist polka by Circus Homunculus.

The beautiful irregular object is “Bridgeport Wooden Block Exploration” by Jane Ni is licensed under CC BY-NC-ND 4.0

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Specific Heat Capacity (GCSE Required Practical)

Happy Christmas! In the last full podcast of 2019, Thomas and Robin chat about one of the core GCSE Practicals: Measuring Specific Heat Capacity. Also, stealth physics in “fun” Christmas lessons.

Timestamps

  • Bikes follow up @ 00:54
  • Stealth Physics “fun” lessons @ 02:10
  • Chatting about measuring Specific Heat Capacity @ 15:50

Summary

Thomas doesn’t like “fun” lessons, and is a bit of a Scrooge, but Robin has a great one on Christmas lights that is much deeper than you think.

A few days ago we talked through doing the Specific Heat Capacity experiment and we talk about the cognitive load, issues and tips around doing this popular and classic practical. Although his drawing skills are as unconvincing as his podcasting skills, Robin shares these diagrams to use (or preferably ‘do better’) as the basis of some low cog-load instructions. Merry Christmas!

Equipment list

Step 1 – put oil in the openings in the metal block
Step 2 – insert heater and thermometer as show
Step 3 – connect the heater to an ammeter and a power supply, then connect a voltmeter in parallel across the heater.

Step 4 – read the current and voltage, then take an initial temperature reading and record as your t = 0 seconds reading. Start the stopwatch.
Step 5 – record the temperature every 30 seconds until the temperature hits 50 celsius.

Join in!

Please share ideas or successes – or indeed questions – on our Facebook Page: https://fb.me/physicstp .  You can also message us via our website contact form at the.physicsteachingpodcast.com, Twitter @physicstp, email using  the address given in the podcast (if we remember) or by leaving a voice memo using WhatsApp or Telegram to the phone number in our Twitter profile, +44 7898 814716 (don’t call the number, nobody will answer, just hold down the microphone icon and speak your message or upload an mp3 or ogg). Don’t forget to tell us your name because we may use your audio in a future episode.

The music we use remains One legged equilibrist polka by Circus Homunculus. The music before and after James is Cantina Rag by Jackson F. Smith.

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