On page 120 of Tipler & Mosca 5th edition there is a worked example involving calculating the coefficient of kinetic friction of a situation. The authors then basically remark on why the final answer doesn't depend on the mass and why the mass cancels, adding at the end that "the net result is that the mass has no effect".
I understand this remark, but what I am a bit puzzled about is why it was necessary. Isn't it already clear by definition that ##\mu_k## doesn't depend on the mass? It only depends on the materials of the objects. On page 118 of the same book when defining ##\mu_k## it says that it depends only on the nature of the surfaces in contact.
Maybe their remark contains a useful idea which I am not seeing? I have attached the relevant worked example + remark.
I understand this remark, but what I am a bit puzzled about is why it was necessary. Isn't it already clear by definition that ##\mu_k## doesn't depend on the mass? It only depends on the materials of the objects. On page 118 of the same book when defining ##\mu_k## it says that it depends only on the nature of the surfaces in contact.
Maybe their remark contains a useful idea which I am not seeing? I have attached the relevant worked example + remark.
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