While trying to get a student to identify the _source_ of the force used to
lift an object (I was trying for muscles) she answered 'mass times
accleration'.
I have presented N2 as ' a = F/m' for some time now, but it quickly
becomes F = ma in the student minds. My choice is based on the idea that
what we are trying to cause or to explain is the acceleration of an object.*
My wording is that the acceleration is caused by the force (more properly
the net force) moderated by the mass. With liberal-arts students I find a
number who can't deal with this simple ratio. Asked how a given
acceleration changes if the force is doubled, they can answer. Asked how a
given acceleration changes if the mass is doubled and all hell breaks loose.
;-(
Rick
* Likewise my favorite of the 'three most important equations in
electricity' is I = V/r