A heavy wheel is to be lifted using a crowbar. To minimise effort, the fulcrum should be placed:
AClose to the load and far from the effort
BFar from the load and close to the effort
CExactly midway between load and effort
DAt the centre of mass of the crowbar
Answer & Solution
Correct answer: A. Close to the load and far from the effort
1. A crowbar is a first-class lever in which the fulcrum lies between load and effort.
2. Mechanical advantage equals effort arm divided by load arm.
3. To make effort small, mechanical advantage must be large.
4. This happens when effort arm is much longer than load arm.
5. So the fulcrum should be close to the load and far from the effort.
6. Options B and C give either smaller or unity mechanical advantage; option D does not relate to lever geometry.
_Source: Selina Concise Physics ICSE Class 10, Ch 1 'Force' (icsehelp.com chapter extract)_
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