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InterviewSolution
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A disc of mass 5 kg and radius 50 cm rolls on the ground at the rate of `10 ms^(-1)`. Calculate the K.E. of the disc. |
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Answer» Given, mass of the disc, `M = 5 kg` Radius of the disc, `R=50 "cm"=(1)/(2)m` Linear velocity of the disc, `v=10 ms^(-1)` `because v = R omega rArr 10 = (1)/(2) omega` `rArr omega = 10 xx 2 =20 "rad s"^(-1)` Also, moment of inertia pf disc about an axismk through its centre, `I=(1)/(2)MR^(2)` `rArr I=(1)/(2)xx5xx((1)/(2))^(2)=(5)/(8)"kg-m"^(2)` `because` Kinetic enegry of translation `= (1)/(2) mv^(2)` `=(1)/(2) xx5xx(10)^(2)=250 J` `because` Kinetic energy of rotation `= (1)/(2) I omega^(2)` `= (1)/(2)xx(5)/(8) xx(20)^(2)=125 J` `:.` Total kinetic energy `- (250+125) J 375 J`. |
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