What is meant by the efficiency of a machine?
A
Ratio of input power to output power
B
Ratio of effort to load
C
Ratio of output work to input work
D
Difference between load and effort
Analysis & Theory
Efficiency is the ratio of output work to input work, usually expressed as a percentage.
What is the formula for efficiency in percentage?
Analysis & Theory
Efficiency (%) = (Output work / Input work) × 100.
What is the maximum possible efficiency of an ideal machine?
Analysis & Theory
An ideal machine has no energy loss, so its maximum possible efficiency is 100%.
Which of the following conditions leads to maximum efficiency?
Analysis & Theory
Maximum efficiency occurs when there is no friction or energy loss in the machine.
What happens to the efficiency of a machine if friction increases?
Analysis & Theory
As friction increases, more energy is wasted, reducing the machine’s efficiency.
If a machine has efficiency of 100%, what can be said about its Mechanical Advantage (MA) and Velocity Ratio (VR)?
Analysis & Theory
In a machine with 100% efficiency, MA = VR.
Why can real machines never be 100% efficient?
A
Because they are too heavy
B
Because they always have some energy loss due to friction and heat
C
Because effort is always greater than load
D
Because they are not calibrated
Analysis & Theory
Real machines have friction and other resistances that cause energy loss, preventing 100% efficiency.
Which type of machine can achieve maximum efficiency theoretically?
Analysis & Theory
An ideal machine, with no energy losses, is a theoretical concept used to define maximum efficiency.
What is the efficiency if a machine does 80 J of useful work out of 100 J input?
Analysis & Theory
Efficiency = (80 / 100) × 100 = 80%.
What is the consequence of using a machine with very low efficiency?
B
It requires more input for less output
Analysis & Theory
Low efficiency means a large amount of energy is wasted, so more input is required for the same output.