A close-coiled helical spring with n coils, mean radius R and diameter d is subjected to an axial load W. What is the compression in the spring ?

• A. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/65-1591-1.png">
• B. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/65-1591-2.png">
• C. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/65-1591-3.png">
• D. <img src="/_files/images/civil-engineering/upsc-civil-service-exam-questions/65-1591-4.png">