Textbook Update

I have made some small changes to my physics textbook. Basically, I have been updating all my old posts so that you can find stuff. What I did was include tags for each topic. For instance, suppose you are looking at projectile motion. Well, I include a link to examples with projectile motion.

Some of the examples may not be the best for that topic, but it is better than nothing. Really, what I need to do (other than finish tagging all my old posts) is to pick one good example for each topic. There is always tomorrow.

More like this

This probably falls into the "ask a stupid question" file ... but bear with this non-physicist.

Today I was out in the yard clearing some invasive vegetation and dying trees. In order to save some effort, I began tossing some of the chunkier sawn off tree stumps onto a pile about 15 metres away rather than walking them down there.

I found that when I threw them caber style (by applying force at the base, or javelin style they didn't travel as far as when I threw them hammer-style (grabbing a branch and swinging them so the stump travelled through an arc with the heaviest part travelling the greatest distance.

What would be the most accurate way to describe the differing effectiveness of each approach referencing laws of motion?

By Fran Barlow (not verified) on 09 Apr 2010 #permalink


This could be a complicated question. The one thing I thought of was that you could do more work on the branch as you throw it over a longer distance - however this would also give the branch more rotational energy.

The other thing I thought of - are these leafy branches? If so, air resistance could play a huge role.

Thanks Rhett

The portions I was tossing were typically cylindrical (but occasionally gently conical and had been trimmed to remove leaves (since I didn't want the shredder fouling or time to be wasted (as I would be paying by the hour). I also wanted to confine the pile to matter that would not pass through my garden mulcher (ie up to about 30 mm in thickness) That said I didn't bother trrimming off short sections branching from the main block. (hence the "handles").

The piecve I was most effective with was one that had a piece coming off it about the thickness of the ropes one secures ships to docks with (and about a foot long). It was joined to a portion of a tree trunk abour 350mm across at its thickest point and was about 400mm in length. When I swung it, I felt the weight transfer forward just as I released with the result that instead of hitting the pile, it flew across the street and into some shrubbery some 40 metres away.

Not all that productive but a lot of fun!

By Fran Barlow (not verified) on 11 Apr 2010 #permalink