The pitch of a screw jack is 0.45cm and the arm is 60cm long. If the efficiency of the Jack is 75/\pi %, calculate the mechanical advantage.
A
400
B
300
C
200
D
150
Verified Correct Answer: C.
Physical Principles & Numerical Solution
P = 0.45cm, L = 60cm, Eff = 75/\pi%
VR
(Screw
system)
=
2\pir
P
=
2\piL
P
M.A
=
Eff% \times VR
100
=
75
\pi
\times
1
100
\times
2\pi \times 60
0.45
=
75 \times 800
300
=
200
Source: Myschool Past Questions Archive (Record #55044)