Question

a brass disc fits simply in a hole of steel plate. the disc from the hole can be lossened if the system​

Answer 1

Remember the aws of expansion by heating. If you heat the steel nearer to the hole then the it will increase in size means ssuperficial expansion should be experienced there thus the hole will be loosened.

Answer 2

$\boxed{Explained\:Answer}$

______________________________

Thermal expansion coefficient of brass is ˜ 20 × 10-6 /°C whereas that of steel is ˜ 15 × 10-6 /°C.

 

Hence brass expands/shrinks faster than steel.

 

So the brass disc from the hole of steel plate can be loosened if the system is cooled.