Determine which coil (top or bottom, or one in the middle) deflects to zero pitch first as the force is increased.

1. A conical compression spring is made from 3-mm diameter steel wire and has an active coil diameter that varies from 25 mm at the top to 50 mm at the bottom. The pitch (distance between coils) is throughout. There are four active coils. A force is applied to compress the spring and the stress always remains in the elastic range.

a. Determine which coil (top or bottom, or one in the middle) deflects to zero pitch first as the force is increased.

b. Determine the force corresponding to the deflection identified in part (a). In other words, determine the force causing displacement of 8 mm.