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

Length of the crowbar = 120 cm

Load arm = 20 cm

Effort arm = 120-20 = 100 cm

MA = Effort arm

Load arm

MA = 100

20

MA = 5

Answer 2

The mechanical advantage of the crowbar is 5.

Given data states that there is a crowbar with 120 cm length and fulcrum of the crowbar is at 20 cm distance from the load. The crowbar is an example of lever belonging to the class I.  

Thereby the fulcrum needs to be situated somewhere in between the two, from the load and the effort. The load arm is given as 20 cm and total length as 120 cm so the effort arm will be  $\Rightarrow \text { effort } a r m=120-20=100 \mathrm{cm}$

Thereby Mechanical advantage $=\frac{\text { effort arm }}{\text { load arm }}$

$\Rightarrow \text { Mechanical advantage }=\frac{100}{20}=\bold5$