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.

Answer 1

A crowbar is a metal bar with a single curved end and flattened points that is used to remove nails or force two things apart. It usually has a minor fracture on one or both ends. Crowbars are frequently used to dismantle boards and open fastened wooden crates. Power is transmitted in an ideal mechanism without being added to or subtracted from. This means the ideal mechanism has no power source, is frictionless, and is made up of stiff, non-deflecting, non-wearing bodies.

Complete step by step solution:
A crowbar is a metal bar with a single curving end and flattened tips, typically with a tiny crack on one or both ends, that is used to remove nails or force two items apart. Crowbars are often used to break apart boards or open nailed wooden boxes.
If a and b are the distances from the fulcrum to points A and B, and ${{F}_{A}}$ is the input force and ${{F}_{B}}$ is the output force, the ratio of the velocities of points A and B is given by $\dfrac{a}{b}$, and the ratio of the output force to the input force, or mechanical advantage, is given by $\text{MA = }\dfrac{{{\text{F}}_{\text{b}}}}{{{\text{F}}_{\text{a}}}}\text{ = }\dfrac{\text{a}}{\text{b}}\text{ = }\dfrac{\text{Effort arm}}{\text{Load arm}}$
This is Archimedes' law of the lever, which he proved using geometric reasoning. It illustrates that the lever amplifies the input force if the distance from the fulcrum to where the input force is applied (point A) is larger than the distance b from the fulcrum to where the output force is applied (point B).
Total length of crowbar = 120 cm
Load arm = 20 cm
Effort arm = 120 − 20 = 100 cm
Mechanical advantage, $\text{MA = }\dfrac{\text{Effort arm}}{\text{Load arm}}$
$\Rightarrow M.A\text{ }=\dfrac{\text{ }100}{20}=5$

Note:
The lever is a moveable bar with a pivot connected to or positioned on or across a fixed point. The lever works by applying forces at various distances from the pivot, or fulcrum. The class of a lever is determined by the placement of the fulcrum. A rotating 2nd-class lever is used when a lever spins constantly. The end-point movement of the lever specifies a fixed orbit in which mechanical energy can be exchanged.