<P> M A = F out F in = η v in v out (\ displaystyle \ mathrm (MA) = (F_ (\ text (out)) \ over F_ (\ text (in))) = \ eta (v_ (\ text (in)) \ over v_ (\ text (out))) \,) </P> <P> So in non-ideal machines, the mechanical advantage is always less than the velocity ratio by the product with the efficiency η . So a machine that includes friction will not be able to move as large a load as a corresponding ideal machine using the same input force . </P> <P> A compound machine is a machine formed from a set of simple machines connected in series with the output force of one providing the input force to the next . For example, a bench vise consists of a lever (the vise's handle) in series with a screw, and a simple gear train consists of a number of gears (wheels and axles) connected in series . </P> <P> The mechanical advantage of a compound machine is the ratio of the output force exerted by the last machine in the series divided by the input force applied to the first machine, that is </P>

How are the input and output forces of the parts of a compound machine related
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