Question

A screw jack of length 12cm is used to raise a car through a vertical height of 25cm by turning a Tommy bar through 50 revolution

calculate the approximate of the screw jack

(π=3-14)

Answer 1

The pitch of the screw jack is

$$p=\frac{25}{50}=0.5\text{ cm}.$$

The approximate velocity ratio of the screw jack is

$$v=\frac{2\pi D}{p}=\frac{2\pi ·12}{0.5}=151.$$