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Question
A crowbar of length 120 cm has its fulcrum situated at a distance of 20 cm from the load. Calculate the mechanical advantage of the crowbar.
Solution 1
Total length of crowbar = 120 cm
Load arm = 20 cm
Effort arm = 120 − 20 = 100 cm
Mechanical advantage M.A. = `"Effort arm"/"Load arm"`
M.A. =` 100/20=5`
Solution 2
By the principle of moments.
Moments of load about the fulcrum = Moment of efforts about the fulcrum
We have: W × 20 = P × (120 − 20)
`"W"/"P"=100/20`
= 5.
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