A spring of stiffness 100 N/mm used in a spring-loaded safety valve of diameter 20 mm on a boiler with the pressure inside the boiler equal to 1 MPa should be initially compressed by
a. 5mm b. 3.14 mm c. 2mm d. 6.28 mm
a. 5mm b. 3.14 mm c. 2mm d. 6.28 mm