A Question from Heat and Thermodynamics

A thermo stated chamber at a height ‘h’ above the earth’s surface and maintained at 30 degree Celsius has a clock fitted with an uncompensated pendulum. The maker of the clock for the chamber mistakely designed it to maintain correct time at 20 degree Celsius. It is found that if the chamber were brought to earth’s surface the clock in it would click correct time. The coefficient of linear expansion of the material of pendulum will be………………..

– Himani