Question

find the centroid of semi-circular section
having outer and inner radio of comm and
16omm respectively​

Answer 1

Explanation:

We can use concept of parts cut out of solid bodies for finding COM =

A

1

−A

2

A

1

x

1

−A

2

x

2

..(1),

Here we use concept of COM of semi circular plate (=

3π

4R

)

now considering full plate of massM and area A

2

=

2

πR

2

2

Then area for part R_1 radius will be A=

2

πR

1

2

now using these in eq 1 we get required COM=

3π(R

2

2

−R

1

2

)

4(R

2

3

−R

1

3

)

=

3π(R

2

−R

1

)(R

2

+R

1

)

4(R

2

−R

1

)(R

1

2

+R

2

2

+R

1

R

2

)

=

3π(R

1

+R

2

)

4(R

1

2

+R

2

2

+R

1

R

2

)

this is required center of mass above the center.