A) 10m
B) 7.5 m
C) 5 m
D) 2.5 m
Correct Answer: A
Solution :
Key Idea: Kinetic energy of cylinder is consumed in doing work against friction in rolling motion. A body of mass m moving with velocity v, possess kinetic energy given by \[\Delta t\] ?...(i) This kinetic energy is utilized in doing work against the frictional forces. \[\overrightarrow{\mathbf{F}}\,\times \Delta t\] ?...(ii) where \[\overrightarrow{\mathbf{F}}\,=m\,\overrightarrow{\mathbf{a}}\] is coefficient of kinetic friction, m is mass, g is gravity and 5 is displacement. Equating Eqs. (i) and (ii), we get \[m=150g=150\times {{10}^{-3}}kg,a=20m/{{s}^{2}}\] where \[\therefore \] Given, \[F=0.15\times 20=3N\] \[=F\,\Delta t=3\times 0.1=0.3N.s.\] \[{{v}^{2}}={{u}^{2}}-2gh\] \[\therefore \]
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