A common measure of the ability of a material to carry load per unit mass is termed strength-to-weight ratio and is calculated by dividing the ultimate tensile strength of the material by its density. This property is key in weight-critical applications, such as aerospace, where many materials with high strength-to-weight ratios are used (e.g., Ni-based superalloys, Ti-based alloys, Al-based alloys, and composites).

Write a function to calculate the strength-to-weight ratio for a given material provided its ultimate tensile strength and density.

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