Question

if the radius of a doorknob is 5.0 cm (input distance) and the radius of its inner rod is 2.5 cm (output distance), what is the mechanical advantage of the doorknob? do not include units in your answer.

Explanation:

Step1: Recall mechanical - advantage formula

The mechanical advantage (MA) of a wheel - and - axle (a doorknob is an example of a wheel - and - axle) is given by $MA=\frac{R}{r}$, where $R$ is the radius of the wheel (input distance) and $r$ is the radius of the axle (output distance).

Step2: Substitute given values

We are given that $R = 5.0$ cm and $r=2.5$ cm. Substituting these values into the formula, we get $MA=\frac{5.0}{2.5}$.

Step3: Calculate the result

$MA = 2$

Answer:

2