Applied Physics: Newton's 2nd Law of Motion

The relationship between an object’s mass, its acceleration and the applied force is force equals mass times acceleration.

Physics is definitely not my subject, but the horses seem bound and determine to further my education, even if we’re going about it in reverse order.  We learned about Newton’s 3^rd law back in May.  (Read it Here)  This week’s lesson, Newton’s 2^nd Law of Motion.

I find the Second Law of Motion a little more complicated.  After all, it involves math.  That’s probably why Nutmeg needed to illustrate it not once, but twice this week.  For the first time since moving the horses home, I got to ride in my future arena, aka “the grass patch.”  Early in the year, I mowed the grass in approximately the location and dimensions of the grand prix jumping arena we will someday install (ha).  Admiral tested it out first with a very easy walk/trot day.  The ground was still a little wet and we were occasionally tearing up the grass, so we played it safe.  We’re also both embarrassingly out of shape so that helped dictate our regimen as well.  Fitness and activity levels aside, we determined the grass patch will make a fine arena and it was great to be riding in circles at home.

Nutmeg was thrilled with the footing the following day and that’s where Newton’s 2^nd Law comes into play.  The relationship between an object’s mass (Nutmeg’s mass = a lot, her weight is 1280 lbs.), its acceleration (halt=0 mph, walk = 4.5 mph, trot = 12 to 15 mph, canter = 20-25, buck = who knows… but you get the idea) and the applied force is force equals mass times acceleration.  So, we’ve got the mass of a very big horse times the acceleration of a very big horse who hasn’t been out on good footing in ages.  Let me tell you, the force is great, so great, the ground was flashing before my eyes and I was praying I stayed in the saddle.  The really great thing about force is that it can be applied in any direction, forward, backward, up, down, diagonal.  Nutmeg made sure I remembered that concept as well with a series of rodeo bronc bucks that rivaled her younger days.  I guess the two trips to the chiropractor have her feeling young and frisky.

Lesson two for Newton’s 2^nd Law came a few nights later.  We spent a large portion of the day preparing for the impending rain.  We hauled and spread gravel on my path up to the pasture to prevent the mud slip-in-slide adventures of the last rain fall.  Then we dug out under the pasture gate and filled in with gravel.  Yes, I’m seriously spoiled by my husband.  That night, as I was bringing the horses and pony inside, Newton’s 2^nd Law got some practical application.  In the very dark, dark a hoof collided with my ankle bone.  The force at which it impacted was great, but I wasn’t sure who to blame.  Remembering Nutmeg’s lesson earlier in the week I did a little math.  A large amount of force would be the product of either large mass and little acceleration or little mass and fast acceleration.  Admiral was ruled out because he wasn’t close enough to inflict damage.  Vaughn weighs all of 500 lbs when wet.  We were walking.  Acceleration was nil.  Big foot’s to blame.  Big surprise.

So, lesson noted.  Physics is very much an applied science.  Sometimes it’s applied to your rear; sometimes to your ankle and sometimes it allows you to soar over cross country fences.  I guess Newton’s 2^nd Law of Motion isn’t all bad.  That’s your Fresh Perspective on Newton’s 2^nd Law.