A screw jack with a Tommy bar of length 12cm is used to raise a car through a vertical height of 25cm by turning the Tommy bar through 50 revolutions. Calculate the approximate velocity ratio of the jack [\(\pi = 3.142\)]
A
21
B
38
C
48
D
151
Verified Correct Answer: D.
Physical Principles & Numerical Solution
P = \(\frac{25}{50} = 0.5\)
V.R = \(\frac{2\pi D}{p} = \frac{2 \times 3.142 \times 12}{0.5}\)
= 151
Source: Myschool Past Questions Archive (Record #33880)