Tag: grass trimmers

Math has a bad reputation and people often say it has no application to everyday life.  I dispute this contention.  I had several bad days recently.  Math came in handy on one of them.

I was trimming the grass in my back yard recently with a string trimmer aka “Weedeater” aka edge trimmer when my mind suddenly wandered. (Quelle suprise.)  Next thing you know I had slashed my left lower extremity.

After I finished hopping around and cursing, I went in and cleaned the wound.  Suddenly a thought occurred to me: “I’m an idiot.”  Then another thought occurred to me, that I could actually use this.  After all, every cloud has a silver lining.  Right?

I counted the slashes and there were ten of them.  I reasoned that in the time it took me to withdraw my leg from the crime scene, the trimmer had made ten rotations.  Then I recalled from the depths of my mind somewhere that the reaction time in situations like this is around 200-250 milliseconds.  Not that you care but a perfect example of this would be when you jerk your hand away from a hot object such as a lump of near-critical U235.  And by the way, you should be more worried about the hefty dose of radiation you would also pick up in that situation.  But that’s for another blog.

Anyway, I dug up an on-line visual stimulus reaction-time tester and tested myself.  It came up at 400 msec but per the site, you have to factor in the lag time introduced by your computer and the internet.  Still, that time was good enough to put me at age 29 according to their nomogram, even though I’m rapidly approaching age 61.  So I felt pretty good about that but I kept going.

Then I Googled (I guess that’s an official verb now) “average reaction time hot object” and it returned the reaction times for a variety of stimuli: visual, auditory, touch, dodging a falling 10-ton weight, etc.  I figured my string-trimmer episode fell into the touch stimulus category so I went for 150 milliseconds (0.15 seconds) for the time it took me to jerk away from the trimmer.

So now I was able to estimate that in the time it took me to react, the trimmer completed 10 revolutions in 0.15 seconds.  That’s 67 revolutions per second or about 4000 rpm.  That’s about where you would upshift in a ’99 Civic, not that you care.

Then I looked up the RPMs for a trimmer (don’t you just LOVE Google?) and lo and behold it ranges from 3000 RPM or so at idle to 10000 RPM at full bore.  I was running the trimmer above idle so I reckoned that my math was OK.  (I probably need to work on the whole “Safety First” concept though.)

You can try this at home but don’t say I told you to do it.  And maybe think about wearing shinguards when you trim your grass, and don’t remove the honkin’ big housing on your trimmer about two seconds after you get it out of the box, like I did.  Just bear in mind that if you leave that housing in place, you won’t be able to do precision trimming.  Everything has it’s price.

You might consider trimming your grass borders the old-fashioned way…

You could also say forget it and consider hiring someone to do your trimming as long as they bring their own equipment.

The other bad day I want to tell you about is the day that began when I walked my dog Mickey wearing the same T-shirt I had worn the day before and also the ratty old shorts I tore up when I tried to run my son off a luge course at Canada Olympic Park.

Anyway, when I got home from dog-walking I raced off to work and forgot to change.  No one at work noticed, if that tells you anything.  FYI, I did shower that morning before I donned my dog-walking outfit.

But it gets worse.  Later on that same day I found myself trying to open one of the doors to the lab by holding an orange plastic folder up to the scanner.  Nothing happened.  Then I realized I should have been using my swiper.

Ooops!  Wrong side!  This is the other side:

There, that’s better.  Things went smoother after I got that sorted out.

Later that day I went to visit my son Drew, his wife Dominique and my grand-daughter Max.

Alexa features prominently in my son’s household.  You know who Alexa is.  She’s that helpful entity wired to Amazon.  Alexa listens to your conversations and will obey your every command.

Drew:  “Alexa, don’t listen to Max.  We don’t need a baby elephant.  Go to sleep.”

Alexa:  “OK Drew. Don’t worry that I might still be listening or anything.  Just saying.”

If she was real I think Alexa would look like this:

Based on my earlier experiences that day and also recalling my misfortune with the edge trimmer, I started to think to myself how many ways things could go wrong if you let Alexa into your life.  Because after Drew told Alexa to go to sleep I immediately began thinking to myself: “What if she really only PRETENDS to go to sleep and continues to listen to everything that goes on?”  And also: “What if she can read minds?”

What could go wrong?

Lots of stuff.  For example, next thing you know a truck could be pulling up in your driveway dropping off a bunch of items Alexa happens to think you might need, such as shinguards, a baby elephant complete with several bales of hay or worse yet-two sub-critical chunks of U235 and a neutron source, complete with instructions:

WARNING: DO NOT SANDWICH THE NEUTRON SOURCE BETWEEN THE CHUNKS OF U235 AND CLAMP THE WHOLE SHOOTING MATCH IN A VISE.  THE BABY ELEPHANT WILL RAPIDLY BECOME THE LEAST OF YOUR CONCERNS…

Never trust anyone named Alexa.  Just saying.

Keep an eye on your RPMs.  And your shins.