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Question
A man uses a crowbar of length 1.5 m to raise a load of 75 kgf by putting a sharp edge below the bar at a distance 1 m from his hand.
- Draw a diagram of the arrangement showing the fulcrum (F), load (L) and effort (E) with their directions.
- State the kind of lever.
- Calculate:
- load arm,
- effort arm,
- mechanical advantage and
- the effort needed.
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Solution
(a)
75 kgf. crow bar
Effort = ?
M.A. = `"L"/"E"`
2 = `("75 kgf")/"E"`
E = `75/2`
E = 37.5 kgf
(b) Class I lever
(c)
- Load arm 1.5 – 1.0 = 0.5 m
- Effort arm = 1 m
- Mechanical advantage = `1.0/0.5 = 2`
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