A unifrom cubeof massm andsidea isplacedon africtionlesshorizontalsurface.Avertical forceF is appliedto the edgeasshowninfigure,matchthe following(most appropriate choice )

A unifrom cubeof massm andsidea isplacedon africtionlesshorizontalsurf

1.	A unifrom cubeof massm andsidea isplacedon africtionlesshorizontalsurface.Avertical forceF is appliedto the edgeasshowninfigure,matchthe following(most appropriate choice )
Answer» Solution :Considerthe belowdiagram Momentof theforce FaboutpointA `tau_(1)=Fxxa` (anti - clockwise ) MOMENT ofweightmg of thecubeaboutpointA , `tau_(2)=mg xx(a)/(2)` (clock wise ) Cubewill not exhibitmotion,if ` tau_(1)= ta_(2)` (`:'` in thiscase , boththe torquewill cancel the EFFECT the effectof each other ) `thetefore "" fxxa= mg xx(a)/(2)implies F=(mg)/(2)` Cubewillroateonlywhen ,`tau_(1)gt tau_(2)` `Fxxa gt mgxx(a)/(2)implies Fgt(mg)/(2)` Let normalreactionis actingat `(a)/(3)` frompoint A , then `mgxx(a)/(3)=Fxxa or F=(mg)/(3)` when`F=(mg)/(4)` whichis lessthan`(mg)/(3)`""`(FLT(mg)/(3))` therewill be no motion . `therefore(a) to (ii)(b) to (III)(c ) to (i)(d) to (iv)`