Old copper wires are melted when they are recycled. Calculate the energy needed to melt 500 kg of copper at its melting point.
Specific latent heat of fusion of copper = 200 kJ/kg

No because a circle or pie graph usually shows percentages you'd need a line graph

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other