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Re: [Phys-l] F causes a



JMGreen wrote:

If I am faced with a block and I push really hard and the block
moves, don't I say that _I_, my push, moved the block? Now, if I
wanted to do some figuring, I might remember F=ma and calculate what
I was deeply concerned about. But during the figuring I would think
force caused the acceleration. If some body came along and said no
no no the acceleration caused the force, I would think that they were nuts.

So how would you assess the following example?

Someone too far distant for you to see throws the block at you. All you know is suddenly a flying block hits you in the face. In your vernacular (which I would say is far more simplistic than the discussion that has been going on), you feel a force as the block hits your face. In fact, the Jim Green I've read for years here would claim that only a force could cause (oops there's that word) his tooth to have been knocked out. Would you not say that the (de)acceleration of the block as it hit you is what caused the force that knocked your tooth out? If not, where did that force come from?


Stefan Jeglinski