BITSAT 2022 Paper

Given, mass of solid sphere =80kg
radius of solid sphere, Rs=15m
radius of circular disc, Rc=20m
and time =1‌hour=60‌minutes=60×60sec
∴ Moment if inertia of solid sphere, Is=

2

5

MR2
=

2

5

×80×(15)2
=7200kg−m2
Similarly,
moment of inertia of the disc, Ic=

1

2

MRc2
=

1

2

×80×(20)2
=16000kg−m2
Rate of change of moment of Inertia =

Ic−Is

t

=

16000−7200

60×60

=

22

9

kg−m2s−1