experiment: (y)our children are ‘powerful’

17/05/2020

Okay, I retrieved another experiment/details teacher-doc from elsewhere and my broken hard-disk – I wrote a draft of this some 12-13 years back or so. (Here’s one on micrometeorites!)

I do these kinds of ‘outdoorsy’ experiments with children, after I complete (and um, after they have assimilated, hopefully) the basic prerequisites. And I wait for a suitable day, when it is not too warm or humid, to do the experiment – not that all these silly thingies ever stopped a child from having some goofing-off fun (and learning, of course!).

It is always fun to do these stuff – with so much cardio vascular pumping/thumping action all around, not to speak of the unspeakable excitement in the children, checking notes, comparing their ‘power’ in Watts etc etc… (not to speak of the gruesome punnable possibilities involving Watts, Vats, Votes, What etc etc)

The following text gives the ‘template’ for doing the experiment. Bored adults at home can also join the kids to figure out how ‘powerful’ they are, in these times of China sponsored COVID-19 programme of lockdowns etc.

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Prerequisites: Basic knowledge of what power, work and force mean; also, basics of gravitational attraction.

Suggested Target group age band: Elementary – or as soon as the children have a general idea of – how power and work are related – and that the energy is the capacity to do work, that is – and that power is the ability to work in a given time-frame etc etc.

Having said that, we also know that, about 100% of us adults are also actually aDolts and clueless. Hence, we can also join the tamasha and experimentally do the experiment.

…It would help if the children knew – how to design, conduct and record properly formed / controlled experiments; if not, this process can be used to test ‘hypotheses’ at the very least. ( like “Duckbar is more powerful/greater than Dabur” in case you want to bring in connections from the dastardly Dughal Distory of our medieval Bharat/India).

Goal(s):

  • Understanding the units of work/energy (Joules), force (Newtons), power (Watts)
  • To know how they are related
  • What are potential and kinetic energies
  • To explore whether there are other kinds of energies
  • Most importantly
    • measuring a rough indicator of physical ‘Power’ of each child
    • understanding as to how this ‘Power’ can be increased with stamina building exercises and constant practice
    • cross-mapping the meaningful stamina building – towards being more ‘Powerful’ in any realm including ‘academics’ (subject to physiological limitations)

Ingredients/Apparatus/Thingies required:

A stop clock (a wrist watch would do too – or may be a smartphone, depending on whether the school ‘policy’ allows that); measuring tape/ruler; weighing machine; a few flights of stairs; n number of pesky children whose energies need to be taken out; the usual notebook and pencil. a non-sleepy, functioning brain for the adult/teacher.

Experimental procedure:

Time how long it takes a child to walk up a set of flights of stairs; measure the height from the bottom to the top of the flights, If needed, measure the height of one step and multiply it by the number of steps. (I usually make use of flights of stairs in a multistory building or the stand-alone overhead water tank with a staircase)

Take the mass (not weight!) of the child (measure it with the weighing machine; wonder why it is called the weighing machine, though – shouldn’t it be called massing machine or something?!).

The idea is that the child is hauling himself up in a given time – which can be a rough indicator of how ‘powerful’ the child is etc.

Computation:

Take the weight of the child in Newtons (mass (= in kgs) X g (= acceleration due to gravity – circa 9.81 meters x second^-2 – for easy computation, you can approximate g to some 10 meters x second^-2)) and multiply the total height scaled. This would give the gain of gravitational potential energy by the child when he/she goes up.

The work done is in Joules – which is actually kgs X meters/second^2 X meters

Now divide this gain in potential energy by time taken (in seconds) to give the child’s power in Watts. All children can do this computation. If there are issues of physical inabilities/disabilities, then the adult would have this particular child do the compute/time etc – so that she/he can feel vicariously powerful too.

Example: A kid ‘weighs’ 30 kilogramss, goes upto a height of 10 meters in 15 seconds.

The child’s ‘Power’ = 30 x 10 x 9.81 / 15 = 196.2 Watts; so approximately the kid (for the current experiment) has had about 200 Watts of Power!

Suggestions:

The children can take turns and measure their power – while one climbs up, the other can time it, etc.

It would be ideal if there are many flights of stairs, but if not one can try climbing the railings of over head tank or if this not available, may be one can even walk.

  • Driving home: Work done = force x distance moved in the direction of the force
  • Driving home: Energy is the capacity to do work
  • Driving home: Power is the energy transferred in a given time; or the capability to do energy transfer in a give time.

Effect:

The linking of the text-bookish understanding of force, power and work to something concrete that all of us do on a daily basis.

And, the fact that we can measure our power output in a fun way. Thusly, the power of wow!.

Questions for discussion: All thru the presentation, questions from children need to be positively encouraged; to elicit the opinions of children the following types of questions can be posed:

  1. What is your weight in Newtons? (mass in kgs x ‘accleration due to gravity’ in meters/second^2)
  2. What would be your weight on say, Moon.
  3. Why can’t I measure the time of my coming down the stairs. (actually you can do that; the thing is there would be a decrease in potential energy and the force of the earth (gravitation) would help you unlike while going up)
  4. What happens when – I carry on my back someone else and walk up? Would he/she have done some work too? Is there a difference in energy of both? What about the power of the person carried?
  5. What could happen if there were no gravity?
  6. What would be the difference if we were doing the experiment on the moon?
  7. If the children run up the stairs as opposed to walking up, does it make a difference to their power? (can it be linked to the formula?)
  8. While walking up, there is some horizontal movement too. How come we are only considering the vertical height travelled?
  9. If they carry an additional weight, would it make a difference to the power or the work done? To know this does something need to remain constant?
  10. If the kid walks horizontally, is he doing any work against gravity? (actually the answer may be is a No for the current level of understanding of the child, but if we consider walking as ‘repeatedly trying to fall and arrest our fall midway’ etc, which actually is the correct thing, the answer is an Yes – we can have interesting discussions around this)
  11. Is there a connection between the power of the individuals and say incandescent bulb wattage ratings such as 100W or 60W or something? Do they actually measure the same? Are we talking about similar things here?
  12. In the same vein, is there any connection to the power output of the vehicles?
  13. If we use or expend/exert similar energy/power while riding bicycles as with walking or climbing, how come we go much faster for the same power output?
  14. What are the various errors that could creep in, what are the various factors that we are either ignoring or keeping constant – in the context of doing the experiment.
  15. What are scalars and vectors, and what is their connection to Malaria.

Anyway.

Eventually the children should be able to zero-in on the principles behind the effect on their own, but if not, they can be given clues and similar effects.

Closure:

There should be definite closure to the demo – repeating and reaffirming the basic principle involved; can take the form of ‘Look, this is what I did and this is what happened. Do we agree that this could be a reason? What do you think happened? Was it <any of the (off tangent) suggestions from the children> or <any of the correct explanations>.’

This will close the activity at the class / environment.

Records / notes:

These should be created by the adults for each instance of the experiment – typically as appendices to the same document so that ‘lessons learnt’ could be captured and disseminated later on. This could help us spot and respond to some interesting diversions or some interesting questions etc etc.

Precautions:

Safety first – the adult has to do the climbing at least once (to see if the stairs are not slippery or corroded – to size up whatever danger that could lurk in there) and if the railings are not safe, then it is better to shift to a better building/water-tank.

Children should not be allowed to crowd around the railing area. No need for any cheerleading or catcalls as this is a ‘scientific’ experiment. ;-)

Comparison of ‘powers’ could be allowed, as long as no bullying/sulking happens.

Suggested additional activities:

The children, as a way of reinforcing their learning, should be goaded into doing some follow-ups; these typically could take the form of the following:

  • Encouraging them to perform the experiment at home – for the benefit of parents. (may be – but during the experiment, the parents should not be besotted with alcohol)
  • Conducting a quiz on the factoids (oral / written) the following day.
  • Extensions that the children can be prompted to explore. Are kinetic and potential energies related? What about walking on a level road?
  • Can the child ‘increase’ its power output – if so how (stamina is the other word for power in the human context and so regular training would help – coupez la difficulte en quatre)
  • Assuming that the kids do the timing/climbing everyday – can the children draw a graph showing how their power is increasing over a period of time?

Sources & notes:

My impromptu experiments with a few adolescent children many years back. I think any self respecting physics book would cover this kind of experiments and therefore there is nothing major or new here at all.

There could be quite a few websites dealing with the stuff. In any case, NO claims to originality are being made here. And, as always, I don’t claim any copyright either!

The purpose of putting up this stuff is to enable others use the method or the madness, if they so desire. (at their peril)

Please feel free to comment on the content and style. Suggestions for improvement of the procedure  or feedback after using the idea are welcome.🙂

(Postscript: this post became too long because I had to annotate it and simplify/elaborate on various steps so that anyone who reads this blog can kinda understand and do/reproduce it at home/their school; and, my patience ran out, and I just wanted to toss it out, so there could be some errors; if so, please correct me!)

END

 

2 Responses to “experiment: (y)our children are ‘powerful’”

  1. rsjay1976 Says:

    Raam, Couple of queries 1) My daughter had a query about work done when going down the stairs. Would it be 10 times lesser the work of going up the stairs as we are going with the gravity. 2) As it is corona times i am tasked with the duties of playing throw balls/volley ball/catch ball .. And a strange thing i found was when doing a quick reflex action of going down on the knees to catch the ball is more difficult than quick reflex action of going up against gravity to catch the ball (Could be because of my non flexible back). But was just curious..


    • Yo. Good that you asked.

      1.1 I dunno how you arrived at that 1/10 work deal while going down. But it is for you to tell me.

      1.2 Work/Energy are scalar thingies. All it matters is force applied on a body multiplied by the movement in the direction of the force. Nothing else. (just think about it)

      1.3 There are lots of internal muscle flexing, bone/body movements that happen, which all obey the laws of motion – but on the body there is only nett gravitational force that happens. That nett force is directed towards the centre of the earth. When we climb up or down – we are doing work as dictated by gravity. (am not talking about internal forces/leverages at all – there is no need to bring them in)

      1.4 Without loss of generality – the work done in going up will be more or less equal to the work done in getting down. (of course this a reasonable simplification as we don’t consider a few other thingies)

      1.5 We humans do not have a good or a reliable ‘sense’ of work done or energy expended; when we feel tired, an x amount of work, which otherwise could be easypeasy, would be terrible. Or when we are not interested in doing that work. When we are in a good mood and not tired, we can lift significant loads – but even lesser loads will ‘seem’ heavier when we are not up to it. This is our nature. (there are evolutionary reasons for this)

      2.1 This is because of lack of practice given to leg muscles. Also body not being in tune with life/universe. Anything in our body, which is not used at all or used only sparsely – atrophies. This is applicable our dicks as well as brains.

      2.2 With sufficient practice (after consulting an ortho), the functionality you desire could be redeemed

      YMMV.


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