1.

A cylinder of mass 10 kg and radius 15 cm is rolling perfectly on a plane of inclination30o. The co- efficient of static friction µ_(s) = 0.25. (a) How much is the force of friction acting on the cylinder ? (b) What is the work done against friction during rolling ? (c) If the inclination θ of the plane is increased, at what value of θ does the cylinder begin to skid, and not roll perfectly ?

Answer»

Solution :Mass of cylinder `m=10kg`
Radius of cylinder `r=15cm=0.15m`
Angle of inclination `theta=30^(@)`
Coefficient of STATIC friction `mu_(S)=0.25`
(a) Frictional force exerted on the cylinder PARALLEL to the surface of slope
`f=(1)/(3)mgsintheta`
`=(1)/(3)xx10xx9.8xxsin30^(@)`
`=(1)/(3)xx10xx9.8xx(1)/(2)`
`=16.3N`
(b) Frictional force exerted on the cylinder perpendicular to the surface of slope = work done against friction force during ROLLING
`W=frcos90^(@)`
`W=0`
(c ) Condition of rolling without SLIDING
`mu=(1)/(3)tantheta`
`THEREFORE tantheta=3mu`
`=3xx0.25`
`=0.75`
`therefore theta=36^(@)54`
`therefore theta~~37^(@)`


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