Elastic Properties of solid:

When you stretch a rubber band or a spring, it returns to its original shape because of elasticity. Hooke's law tells us that the force needed to stretch something is directly proportional to how far you stretch it. Young's modulus measures how stiff a material is—steel is stiffer than rubber, so it has a higher Young's modulus.

When you compress or stretch a spring, you store energy called elastic potential energy. The work done equals half the force times the distance moved. Think of a Nigeria-made mattress spring: compress it and it stores energy that pushes back.

Thermal conductivity describes how quickly heat travels through a material. Black body radiation is energy emitted by hot objects. Solar energy collectors use these principles to capture the sun's heat efficiently. A black painted surface absorbs more heat than a white one, which is why many Nigerian homes use black water tanks on roofs.