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It seems to me that force is far more observable than is acceleration. I
experience and feel forces--run into a wall or sit in a car and have it
speed up, for example. Yes, there are accelerations involved, but what I
feel are forces on me. These seem to me to directly observable--very
Here's a problem. Drop a ball on a coil spring. At what point will the
acceleration on the ball be zero? Most students and many physicists will
say that it is when the spring is fully compressed. WRONG! It is when
the net force on the ball is zero. At that instant the ball is still
moving downward and compressing the spring.
I think there might be some advantage, therefore, to teaching forces
first then kinematics. However, a better approach might be to integrate
them more than is presently done.
Now granted, all the things I had done before *had gotten them to the
point that they had two sets of discordant explanations, each of which
they thought ought to be true.* THIS CONDITION IS WHAT IS REALLY NEEDED
IN ORDER TO MAKE CONCEPTUAL PROGRESS.