Thermal properties of materials

[Spakfilla]

Hey came across this question in my physics textbook. If the surface of a material is under compression, is it hot or cold relative to the body of the same piece of material? Unfortunately their explanation doesn't make any sense what so ever! Would anyone like to give an explanation that makes sense??

 

[flatmaster]

The act of compressing the metal will heat it. However, it will soon cool the the temperature of the rest of the metal. Keeping it under compression will not keep it hot. Take a metal coat hanger or paperclip and bend it quickly. It will become hot where it was bent. However, it should soon cool to the ambient temperature.