Question

In a class $3$ lever, the distance between the effort and the load point is $25\text{cm}$, and the load arm is $0.75\text{m}$ long. Find the length of the effort arm and then calculate the mechanical advantage of the lever. $\left[5\text{marks}\right]$

Answer 1

Given:
Class $3$ lever, Load arm $>$ Effort arm and MA $<$ 1
Load arm $=0.75\text{m}$
Distance between the load and the effort points $=25\text{cm}=0.25\text{m}$
Effort arm $=$ (Load arm) $-$ (distance between them)
$=0.75-0.25=0.5\text{m}$
$\left[2.5\text{marks}\right]$

Now we know the effort arm as well as load arm so mechanical advantage can be obtained as,
$\text{MA}=\frac{\text{Effort arm}}{\text{Load arm}}=\frac{0.5}{0.75}$

$⟹\text{MA}=0.66$
Hence, the effort arm is $0.5\text{m}$ and the mechanical advantage is $0.66$ which is less than $1$.
$\left[2.5\text{marks}\right]$