For Actual Lifting Machine

Ans: option B

For actual lifting machine, the mechanical advantage is less than the velocity ratio.

Solution:

Mechanical advantage: In a lifting machine, the ratio of load lifted to the effort applied is known as mechanical advantage.

M.A. = Load lifted (W) / Effort applied (P)

The efficiency of a lifting machine: it is the ratio of mechanical advantage to the velocity ratio of the lifting machine.

Efficiency(η) = Mechanical advantage  (M.A.) / Velocity ratio (V.R.)

For an ideal lifting machine, the efficiency is 100% i.e. equal to one. Hence, for an ideal lifting machine;

Mechanical advantage  (M.A.) = Velocity ratio (M.A.)

For an actual lifting machine, the efficiency is less than one. Hence;

1>Efficiency(η)

1 > Mechanical advantage  (M.A.) / Velocity ratio (V.R.)

Mechanical advantage  (M.A.) < Velocity ratio (M.A.)

From the above expression it is clear that, for the actual lifting machine, the Mechanical advantage is less than the velocity ratio.

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