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two bodies having the same mass 5 kg each have different surface area 20m^{2} and 10m^{2} in contact with a horizontal plane.if the coefficient of friction is 0.4 the force of friction that comes into play when they are in motion will be in the ratio?

Frictional force depends only on the type of surface and the normal acting force.

IT DOES NOT DEPEND THE SURFACE AREA OF CONTACT

${F}_{MIN}={\mu}_{S}N\phantom{\rule{0ex}{0ex}}N=Mg\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}{F}_{MI{N}_{A}}=0.4\times 5\times 10\phantom{\rule{0ex}{0ex}}{F}_{MI{N}_{B}}=0.4\times 5\times 10\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}or\frac{{F}_{MI{N}_{A}}}{{F}_{MI{N}_{B}}}=\frac{1}{1}\phantom{\rule{0ex}{0ex}}$

Regards.

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