Question

give one example to show that heat is a form of energy

Answer 1

nergy is the capability to do work. To show heat is a form of energy. Take a gas in an enclosed container. Supply heat to the container, the velocity of the gas molecules will increase depending upon the temperature and the force on the walls of container will increase. Now if one of the walls of container is flexible , the volume of the container will increase as gas molecules will push this wall with more force than before the temperature rise. 

Therefore the work done will depend upon the temperature or the amount of heat you supply to the system.

Answer 2

bulbs in our houses