Question

The actual mechanical advantage of a pulley is 2. The pulley has 3 supporting strings. What is the efficiency of the pulley?

50%
66%
100%
150%

Answer 1

66 %

Step-by-step explanation:

The efficiency of a pulley is equal to the ratio between the Actual Mechanical Advantage (AMA) and the Ideal Mechanical Advantage (IMA):

`\eta = (AMA)/(IMA)`

In this problem, we have:

- The AMA of the pulley is 2 (given by the text)

- The IMA of the pulley is 3 (the pulley has 3 supporting strings, so its IMA is 3)

Therefore, the efficiency is

`\eta=(2)/(3)\cdot 100=0.66 \cdot 100=66 \%`

Answer 2

Efficiency is the ability to avoid wasting energy, materials, money, time, and effort in producing a desired result. We know the formula to find the answer AMA/IMAx100. Three supporting strings should have given M.A. of 3 provided that this is without friction. Since there are only 2, the efficiency is 2/3 = 66%.