efficiency of a lever is never 100% or more. give reason
Answers
Answer:
A lever will never retain 100% torque because it will always lose some tiny (sometimes immeasurable) percentage of power due to the lever bending. If the lever in question operates on one or more hinges, friction also comes into play, causing a loss of energy in the form of heat.
Answer:
Most simply, because nothing is 100% efficient.
Okay, got that out of the way... Now, practically, why are the simple machines not 100% efficient?
We do a lot of our work with "points" and "spherical cows " to simplify things. This helps us understand the problem/mechanics, but leaves out many of the "dirty" fundamental truths.
These fundamental truths come in many varieties, but in this specific case, The answer is friction...
Think about it:
a wheel and axle - friction of the rotating member against the non-rotating member (even the wheel against the ground). A pulley is just an extension of a wheel - friction between the rope and the pulley, more between the axle and the block.
An inclined plane - friction between the object on the plane and the plane itself. A screw is a special case of an inclined plane.
A wedge - again, friction (and this is very handy for door stoppers)
A lever - friction against the thing being moved, even with a fulcrum.