A lift is moving downwards with an acceleration equal to acceleration due to gravity. A body of mass $m$ kept on the floor of the lift is pulled horizontally. If the coefficient of friction is $\,\mu $, then the frictional resistance offered by the body is
A lift is moving downwards with an acceleration equal to acceleration due to gravity. A body of mass $m$ kept on the floor of the lift is pulled horizontally. If the coefficient of friction is $\,\mu $, then the frictional resistance offered by the body is
$mg$
$\mu mg$
$2\mu mg$
Zero
A lift is moving downwards with an acceleration equal to acceleration due to gravity. A body of mass $m$ kept on the floor of the lift is pulled horizontally. If the coefficient of friction is $\,\mu $, then the frictional resistance offered by the body is
$(N=\text { normal, } m=\text { mass of object, } a=$ acceleration of lift)
$m g-N=m a$
$N=m a-m g$
$(\text { given } a=g)$
therefore $N=0$
friction $=u . N$
hence friction $=u .0(\mathrm{N}=0)$
$=0$
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