A screw Jack has 90 threads to the meter. The effort is applied at the end of an arm 20cm long. What force must be applied to lift a load of 150 newton

one turn lifts the load 1.1 cm ... one 90th of a meter

in one turn , the end of the arm moves ... 20 cm * 2 * π

(40 π / 1.1) is the force amplification

applied force is ... 150 N / (force amplification)