Question

what is the ima of the compound machine below where a movable pulley is pulling up on a second - class lever? (precision of 1)
hint: when determining ima for complex machines, you multiply the imas of the individual machines in the system.

Explanation:

Step1: Find MA of movable pulley

The mechanical - advantage (MA) of a movable pulley is 2.
$MA_{pulley}=2$

Step2: Find MA of second - class lever

The formula for the mechanical advantage of a lever is $MA_{lever}=\frac{d_{effort}}{d_{resistance}}$. Here, $d_{effort} = 12.0$ ft and $d_{resistance}=4.0$ ft. So, $MA_{lever}=\frac{12.0}{4.0}=3$.

Step3: Find MA of compound machine

For a compound machine, the overall mechanical advantage is the product of the mechanical advantages of the individual machines. So, $MA = MA_{pulley}\times MA_{lever}$.
$MA=2\times3 = 6$

Answer:

6