1. A screw driver with a 1.5 inch diameter handle is used to install a 1/4-20 UNC screw. Determine the circumference where the effort is applied.

2. What is the ideal mechanical advantage of the screw and screwdriver system?

3. How much force can ideally be overcome if 10 Ib of effort force is exerted?

1. Circumference of the handle (where the effort is applied) is pi times diameter.

C = πd

C = 1.5π inches

C ≈ 4.71 inches

2. Mechanical advantage is the ratio of distance in over distance out.

MA = din / dout

MA = 1.5 / 0.25

MA = 6

3. Mechanical advantage is the ratio of force out over force in.

MA = Fout / Fin

6 = Fout / 10 lb

Fout = 60 lb