A crow-bar of length $2.0$ m is used as a machine to lift a box of $100$ kgf by placing a fulcrum at a distance of $0.1$ m from the box. Calculate the effort required.

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Solution

Length of crow bar = 2m
length of load arm = 0.1M
length effort arm = length of crow bar -length of load arm
$= 2 - 0.1 = 1.9 m$
so, velocity ratio = length of effort arm/length of load arm = 1.9/0.1 = 19
use formula, velocity ratio = load/effort
19 = 100kgf/effort
effort = 100/19= 5.26 kgf
hence,5.26 effort is required.

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A crow-bar of length 2.0m is used as a machine to lift a box of 100 kgf by placing a fulcrum at a distance of 0.1m from the box. Calculate the effort required.

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