(a) The uses of polar satellites include: (i) for location identification (ii) to collect data on climate change (iii) observe and predict a natural disaster (iv) use for communication. (b) The slope of a graph of tensile stress against tensile strain represents the modulus of elasticity, also known as Young's modulus. Young's modulus quantifies the stiffness of a material. A steeper slope indicates a stiffer material, while a flatter slope indicates a more flexible material.