The effort applied to move a load is 15 units and the mechanical advantage is observed to be 3. Find the load.

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RRB ALP Fitter 23 Jan 2019 Official Paper (Shift 3)

Answer 1

Concept:

Mechanical Advantage:

In a simple machine when the effort(P) balances a load (W), the ratio of the load to the effort is called MA.
\(M.A = \frac{{Load}}{{Effort}} = \frac{W}{P}\)

Velocity Ratio:

It is the ratio between the distance moved by the effort to the distance moved by the load.
\(V.R = \frac{{distance\;moved\;by\;the\;effort\;\left( {{d_P}} \right)}}{{distance\;moved\;by\;the\;load\;\left( {{d_w}} \right)}}\)

Efficiency:

It is the ratio of output to input. In a simple mechanism, it is also defined as the ratio of mechanical advantage to the velocity ratio.
\(\eta = \frac{{Output}}{{Input}} = \frac{{M.A}}{{V.R}}\)
In actual machines, a mechanical advantage is less than the velocity ratio
In an ideal machine, the mechanical advantage is equal to the velocity ratio.

Calculation:

Given:

Effort (P) = 15 units, MA = 3

\(M.A = \frac{W}{P}\)

\(3 = \frac{W}{15}\)

Load, W = 45 units