Systems of Particles and Rotational Motion

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Question : 31
Total: 33
A cylinder of mass 10 kg and radius 15 cm is rolling perfectly on a plane of inclination 30°. The coefficient of static friction µs=0.25.
(a) How much is the force of friction acting on the cylinder?
(b) What is the work done against frictionduring 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?
Solution:  
Mass of cylinder M=10kg, Radius of cylinder, R=0.15mAngle of inclination, θ=30°, Coefficient of static friction, µs=0.25
(a) Force of friction on the cylinder is given by
F=
1
3
m
g
sin
θ

=
1
3
×10
×9.8
×sin30°

=
1
3
×10
×9.8
×
1
2
=16.3N

(b) During rolling the point of contact is at rest. Therefore, work done against friction is zero.
(c) The cylinder skids (does not roll) when
µs=
1
3
tan
θ

tanθ=3µs =3×0.25=0.75
θ=36.87°37°
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