20) Which one is the example for transmission of motion using thread

21) Which type of thread is used in screw jack spindle?

22) A thread is represented as M12 x 1.5. What does represent the letter 12?

23) Which method of holding is used for lengthy work to avoid over hanging?

24) Calculate the change gear required to cut 4mm pitch thread in a lathe having lead screw of 4mm (lathe stud gear (driver has 50 teeth)