Question

A pulley system has five pulleys in all and is 90% efficient such that it lifts a load of 1000 N. Answer the following question:

The effort required to lift the load is:

Options

• 218.8 N

• 220.0 N

• 222.2 N

• 224.4 N

Answer 1

222.2 N

Explanation:

Given:

Total number of pulleys (n) = 5

Therefore, Velocity Ratio (VR) = 5

Efficiency (η) = 90% = 0.90

Load (L) = 1000 N

Formula:

\[ \text{Efficiency } (\eta) = \frac{\text{Mechanical Advantage (MA)}}{\text{Velocity Ratio (VR)}} \]

MA = η × VR

= 0.90 × 5

= 4.50

\[ \text{Mechanical Advantage (MA)} = \frac{\text{Load (L)}}{\text{Effort (E)}} \]

\[ \text{Effort (E)} = \frac{\text{Load (L)}}{\text{MA}} \]

\[= \frac{1000}{4.50}\]

\[= \frac{10000}{45}\]

= 222.2 N