Now we’re talking! This is how a locomotive can pull a long train of cars with a much greater mass. The engine is pulling forward using steel-on-steel static friction, which is pretty high (0.74), giving it good traction. And the cars have a resistive kinetic friction force with a coefficient that is orders of magnitude smaller.
航拍青海湖：冰水相映成趣，高原春色如诗如画
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How much information is in DNA? ·