Fill a Styrofoam cup with very hot water ( or Coffee). Take objects made of different materials, such as a metal spoon, a wooden pencil, a plastic pen or a glass rod. Put one end of each object into the water and answer following questions. Required:
a. How close to the surface of the water do you have to hold the object for it to feel noticeably warm to the touch?
b. From observations, which material would you judge to be the best conductor of heat? Which is the worst?
c. Rank the materials according to their ability to conduct heat from best to worst.

Explanation:

a ) A good conducting material conducts heat easily from one point to another . So the metal spoon which is good conductor will become hot easily by conducting heat from hot water to tip of the spoon . So even after touching the far end of spoon , we can feel the heat of the hot water in the cup . For other material like wood or plastic we have to hold the part which is  very close to water to feel heat of water .

b ) The best conductor will be that which touches hot even when we touch its farthest  end . Hence metal spoon will be best conductor . Plastic pen will be worst conductor because even touching its part close to hot water , we do not feel much heat .

c ) metal spoon > glass rod  > wooden pencil > plastic pen .

less than one you can't create energy

+15-35=-20

going in opposite directions