455) A column of length l is fixed at both ends. The equivalent length of the column is

456) A spring of stiffness 1000 N/m is streteched initially by 100 mm from the undeformed position. The work required to stretch it by another 100 mm is

457) A feather key transmits a turning moment and permits axial movement also.

458) The width of the pulley should be __________ width of the belt.

459) In a boundary lubricated bearing, there is a __________ of lubricant between the journal and the bearing.