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Grade 12th passMechanics

A disc of radius R, mass M lies on smooth horizontal surface. Two persons of equal mass m standing on diametrically opposite points. Both persons start moving in same sense, then find angle rotated by disc when both persons complete round trip?

Profile image of Subhasish
9 Years agoGrade 12th pass
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1 Answer

Profile image of Vikas TU
9 Years ago
In same sense as it has been mentioned in the qstn. assuming both v speed as clockwise (let),
the disc to be assumed as a rectangular piece of length 2*pi*R and width R (ct from the first person standing)
then from, 
m1 x1 =  m2  x2 we get,
M * x = m * (2*pi*R – x)
x = 2M*PI*R/(M+m)
This is due to one person.
Due to two persons the total angle would be=>
x = 4M*PI*R/(M+m)