suppose you cut a small gap in a metal ring. if you heat the ring, will the gap become wider or narrower?

Answer 1

Wider, because the "hole" inside the ring gets bigger, forcing the ends apart -- yes, even though the metal has expanded under heat. Metal expands IN ALL DIRECTIONS, not just in the linear direction of the ring.

My daughter and I tested this out when installing wrist pins in the engine of my MGB some ten-plus years ago. The pins are an exact fit, so to assemble them, you heat the piston (which has a hole in it) and cool the pin that goes into it. We used Mom's hair dryer to heat the pistons and the freezer to cool the pins.

When both were the same temperature, the pins wouldn't go in the piston. Then we heated the piston and chilled the pin and it slid right into place.

Holes get bigger when the metal they're in expands, and the metal expands uniformly -- so the gap will expand as well.

Answer 2

That's a really good question - since most metals expand when heated the basic assumption would be that the gap would become narrower as the metal expands.

But frankly I'm not sure, as all of the metal would be expanding in a potentially identical manner around the ring... in which case it would remain the same..........

I suppose I should look up various metals and alloys to see how they behave huh?

Hmmm....

-dh

Answer 3

Assuming the metal has a positive thermal expansion, and that it is in an unstressed state... the whole ring expands proportionally. Therefore, the gap gets wider.
Although the circumference is increasing, so is the radius - in exactly the same proportion. Therefore the angle subtended by the gap stays the same.

Answer 4

Its obvious that gap will become wider because in nature every thing will try to prevent its change, so as you supply heat energy to cut ring, it will try to expand its shape and gap between become wider

Answer 5

The Gap will widen if uniformly heated. The whole ring basically gets bigger- with same relative propertions remain. Therefore the gap will be larger than earlier.

Answer 6

Agrees with AnswerMan and everyone else who agrees with him.

This is similar to another question, that of drilling a small hole into a large solid block of metal and then heating the block uniformly. The hole gets larger, not smaller.

Uniform heating, in the absence of mechanical restraint, produces uniform dimensional change. Every feature of the heated object becomes larger in proportion to its original size.

Answer 7

The gap should become narrower... we have already done that experiment... and as far as I remember it gets narrower

Answer 8

it would expand because if we give heat energy the kinetic energy of the molecules of the metal will inc. leading to expansion of the gap

Answer 9

heat expands metal. the gap will be narrower.

Answer 10

depends on how and where you heat the ring, if its done evenly then the gap will increase