stand up,speak up,and save some energy

Friday after solat Jumaat, while putting on my sandals, I endured a rather unpleasant experience. Because of the nature of my sandals - let’s just say because of its, well, form - I had some difficulty putting it on. So I took my time. A little bit too long for some people, I guess, because I also happen to be stepping on someone else’s sandals. It wasn’t deliberate, really. It just happened. Because there were lots of people around so it was hard for me to find my bearing. So this guy, instead of telling me to step away or something, simply yanked his sandals from under me, which threw me somewhat off balance. No injury though, fortunately (OK I didn’t even fell or whatever. Was being dramatic).

Now, a lot has been said about letting people know what you want, as-in; it’s better to ask for something rather than use force to get it. And right then I think I was presented with a perfect example. And so right here right now, being the physics teacher that I am, I shall use numbers to explain why it’s better to say something (that is; ask for something) than use force (this is not to say that it is better to say rather than do. In most situations anyway. *Note: '^' = to the power of, and pi = 3.142);

(Those who don't like maths, and/or those who think that visiting people's blogs and actually look at maths calculations is serial-killer-y can skip most of what's under this sentence and just read the words and numbers in bold)

Condition 1: guy opted to tell me to get off of his sandals;
I considered that this guy wanted to be really hostile, so he used a rather loud voice, up to 75 decibels, so that Intensity of sound, I
= log ^-1 (75/10) 1 x 10^-12
= 3.2 x 10^-5 W/m^2

And that the ear tunnel leading to my eardrum is quite large so that Area of tunnel, A
= pi(r^2), where r = ± 2.6 mm.
= pi(2.6 x 10^-3)^2
= 2.1 x 10^-5 m^2

Which then leads us to the calculation of Power of sound, P
= IA
= (3.2 x 10^-5)( 2.1 x 10^-5)
= 6.8 x 10^-10 W

And, say, he speaks rather slowly, in the sense that saying; “beb, ko tengah pijak selipar aku. Blah sebelum aku marah!” took him, say, 2 minutes (which is an absurdly long time but hey, I’m trying to prove a point here). Work done, W
= Pt
= (6.8 x 10^-10)(2 x 60)
= 8.2 x 10^-8 J

Condition 2: guy used force instead;
OK now let’s compare that to ‘throwing me off balance’. To do that we must first have my
Mass, m = ± 60 kg

Once we have that, we can make other assumptions; say he only needed to ‘lift’ me up a short distance, say 2 mm (which is also a rather absurd value, but what the hell), so that
Distance to be thrown, s = 2 x 10^-3 m

With standard gravitational acceleration, g = 9.81 m/s, Work done, W
= Fs
= mgs
= (60)(9.81)(2 x 10^-3)
= 1.2 J

Result
Now, computing the percentage difference, we’ll arrive to the value = 99.99999317 %

!!!!

I rest my case.