Q1: The ratio of coil diameter to wire diameter of a spring is called the spring

ANS:A - index

In the context of springs, the spring index refers to the ratio of the mean coil diameter to the diameter of the wire from which the spring is formed. Here's how it's calculated: Spring Index = Mean Coil Diameter / Wire Diameter The mean coil diameter is typically measured by taking the average of the inside and outside diameters of the spring coils. The wire diameter is simply the diameter of the wire used to make the spring. The spring index is an important parameter in spring design because it influences various characteristics of the spring, including its stress distribution, stiffness, and ability to withstand loads without deforming permanently. Springs with a higher spring index (larger mean coil diameter relative to wire diameter) tend to be more flexible and have a lower spring rate, meaning they compress more easily under load. On the other hand, springs with a lower spring index (smaller mean coil diameter relative to wire diameter) are stiffer and have a higher spring rate, requiring more force to compress them. Understanding the spring index is crucial for designing springs that meet specific performance requirements for a given application, such as in automotive suspension systems, industrial machinery, or consumer products. Different applications may require springs with different spring indices to achieve the desired balance of stiffness, durability, and cost-effectiveness.