Question

5. A circular plate of uniform thickness has a diameter of
28 cm. A circular portion of diameter 21 cm is removed
from the plate as shown. O is centre of mass of
complete plate. The position of centre of mass of
remaining portion will shift towards left from 'O' by
(a) 5 cm
(c) 4.5 cm
(b) 9 cm
(d) 5.5 cm​

Answer 1

Answer:

c.4.5cm

Explanation:

Y

CM

=

m

1

+m

2

m

1

x

1

+m

2

x

2

0=

m

1

+m

2

ρπ(10.5)

2

t×3.5+ρπ(14

2

−10.5

2

)tx

2

Here πr

2

t is volume and mass is written in terms of density times volume, where ρ is the density of plate material and t is the thickness of the plate.

x

2

=

14

2

−10.5

2

10.5

2

×3.5

x

2

=4.5 cm