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HELP Required on Science Demos!
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PlainName:
 :-+

Small point: in the elastic band demo I think it would have been a bit better to hold the left side (that is, the bit that stays under the camera) with something that isn't your hand. Reason being that your hand warms it up, and when you stretch it you're pulling that warmed part into view so it's not obvious whether the demonstrated heat is from your hand or stretching. If it were pure stretching you'd expect a more or less even spread, whereas it is definitely at body temperature close to your finger. Maybe it would be sufficient to either ack that, or move that hand out of view so only the middle of the elastic band is shown.
Kleinstein:
The effect of the crystal frequency changing is especially large with the tuning fork types (e.g. 32 kHz). There is explaination is also relatively simple: when pointing down the arms will see the normal elastic restoring force and additionally a resoring force like for a pendulum. When pointing up, the grativity part makes the position less stable and lowers the frequency.
The more disc like quartz crystalls are less susceptible and the temperature in the crystal oven can have an effect too.
If the watch is used a tuning fork type 32 kHz crstal (not all do, some also use 4.192.... MHz more disc type), chances are if would be in the horizonal when the watch points up or down, so not much change in that special case.

AFAIK they used such systems with 2 relatively large (to get a stronger effect) tuning fork type crystalls to acutally measure the strenght of the gravitational field. AFAIK this was used as an additional navigation help for nuclear submarines.

The point of elastic collision is not wether all the momentum is transfered, but it is about conserving the energy or not.
The 2 cars on the rail  have quite a lot of friction. So good to show the more static part, but not that great for the collisions.
DrG:
I watched the whole video and I think it is good, but that may have little bearing on a viewing by a 10-11 year. Additionally, there is no standard 10-11 year old, so one aspect is whether you simply want to “reach” as many as possible (lowest common denominator) or concentrate on feeding those that want more of that material.  I think that it is a legitimate differentiation and it is difficult to do both.

We all show some interest in seeing something that we can’t “normally” see because it is essentially mind-expanding. The IR cam does that beautifully. It was mentioned that you might not hold the rubber band in your hand because of the visual heat transfer. You could work that to your advantage by using tongs first and then your hands. After which, the demonstration can proceed as you have done.

The magnets would benefit by a similar visualization (I am sure you know how better than me, https://www.coolmagnetman.com/magvisual.htm).

So, when you get to gravity, the effect on quartz oscillators requires a transition, and it is difficult, but the demonstration works well I think. The challenge is in not going too far explaining an oscillator and time keeping and rubidium. Maybe the way you are doing it is fine – I am thinking that you will get declining attention/understanding at that point, but that may not be a bad thing – feeding those that want more of that material …..i.e., sometimes it is difficult to “see” forces but we can tell they are there….

A small point is consistency of language. At ~ 5:20 you say “the energy is removed” and I wonder about how language-careful you have to be and which words they hang on.

I have given many presentations to many adults and when you have a fixed amount of time and detailed information, I always had a sinking feeling about lying, not to be deceptive, but because the alternative is to take up all the time with prerequisite detailed explanations. My point is to somehow, streamline and simplify oscillators and frequency.  Sitting here, drinking coffee, I considered a metronome as an introduction – but I don’t know if that would work.

Lest anyone thinks I am being too critical, let me state outright that if you did not change anything, the presentation has value and is better than many I had as a 10-11 year old (and yes, I do remember).
EEVblog:

--- Quote from: dunkemhigh on October 04, 2021, 01:07:36 pm ---Small point: in the elastic band demo I think it would have been a bit better to hold the left side (that is, the bit that stays under the camera) with something that isn't your hand. Reason being that your hand warms it up, and when you stretch it you're pulling that warmed part into view so it's not obvious whether the demonstrated heat is from your hand or stretching. If it were pure stretching you'd expect a more or less even spread, whereas it is definitely at body temperature close to your finger. Maybe it would be sufficient to either ack that, or move that hand out of view so only the middle of the elastic band is shown.
--- End quote ---

Yep, realised that. Will change it on the day.
RJSV:
I'm thinking 'EXPLOSIONS...REALLY BIG'..Uh maybe...
  For, tellem you have a 'couple explosions, maybe', as kids really appreciate you have a fun deal, making safe distance from audience.
   A really good smooth-talker can also get audience involved, friendly: "Now, remember to hold your ears, those of you near."
OR: ,"It's only a frozen nitrogen shrink-tube, shatters when warms back up..."

   Forces, you want a 'teeter-todder' lever, DEMO the classic 'weight times lever arm' equivalencies.
Also, some 'air' related force per square inch.
At 14 pounds, per SQ inch, calculate the AIR PRESSURE exerted on one side of a normal sized door.
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