The efficiency of a machine is always less than 100% because the
A
work output is always greater than the work input
B
load lifted is always greater than the effort applied
C
effort applied is always greater than the load lifted
D
velocity ratio is always greater than the mechanical advantage
Verified Correct Answer: D.
Physical Principles & Numerical Solution
In real-world machines, due to factors such as friction, deformation, and other losses, the mechanical advantage is always less than the velocity ratio:
MA < VR
This means that the work output (useful work done) is always less than the work input (energy supplied), leading to efficiency being less than 100%.
Source: Myschool Past Questions Archive (Record #1509)