Heat Effects on an Aluminum Annular Ring

[Xamfy19]

An annular ring of aluminum is cut from an aluminum like attached.

When the ring is heated,

1)the hole decreases in diameter
2)the area of the hole expands the same percent as any area of the aluminum
3)the area of the hole expands a greater percent than any area of the aluminum
4)linear expansion forces the shape of the hole to be slightly ellipitcal
5)the aluminum expands outward and the hole remains the same in size

I know the answer isn't 3), but I didn't get the answer. Thanks.

 

[holly]

It's #2; the hole expands same amount as the rest.

 

[turin]

Imagine the annulus as composes of many tiny radial rectangles. Consider what happens to all four edges of the rectangles. Consider what that means for the circumference of the hole. Translate that into an effect on the diameter and area of the hole.

 

[Xamfy19]

Thanks a lot

Thanks for all of you posted the reply.