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4-2.Friction
medium
A body of mass $\mathrm{m}$ is kept on a rough horizontal surface (coefficient of friction $=\mu$ ) A horizontal force is applied on the body, but it does not move. The resultant of normal reaction and the frictional force acting on the object is given by $\mathrm{F},$ where $\mathrm{F}$ is
A
$|\overrightarrow{\mathrm{F}}|=\mathrm{mg}+\mu \mathrm{mg}$
B
$|\overrightarrow{\mathrm{F}}|=\mu \mathrm{mg}$
C
$|\overrightarrow{\mathrm{F}}| \leq \mathrm{mg} \sqrt{1+\mu^{2}} $
D
$|\overrightarrow{\mathrm{F}}|=\mathrm{mg}$
(NEET-2019)
Solution
$\mathrm{N}=\mathrm{mg}, \mathrm{F}=\mathrm{f}$
Resultant $=\sqrt{\mathrm{N}^{2} +\mathrm{f}^{2}} =\sqrt{(\mathrm{mg})^{2}+\mathrm{f}^{2}} \leq \mathrm{mg} \sqrt{1+\mu^{2}}$
Standard 11
Physics
