Question

With reference to the terms mechanical advantage, velocity ratio, and efficiency of a machine, name and define the term that will not change for a machine of a given design.

Answer 1

Mechanical Advantage$\left(\mathrm{ME}\right)$: It is the ratio of the load$\left(\mathrm{L}\right)$ to the effort$\left(\mathrm{E}\right)$.

$\mathrm{ME}=\frac{\mathrm{L}}{\mathrm{E}}$

Velocity Ratio$\left(\mathrm{VR}\right)$: It is defined as the ratio of the velocity of the effort $\left(V_{\mathrm{E}}\right)$ to the velocity of the load$\left(V_{\mathrm{L}}\right)$

$\mathrm{VR}=\frac{{\mathrm{V}}_{\mathrm{E}}}{{\mathrm{V}}_{\mathrm{L}}}$.

Efficiency$\left(\eta \right)$: It is defined as the ratio of the work done by the machine $\left(\mathrm{Woutput}\right)$ to work done on the machine $\left({\mathrm{W}}_{\mathrm{input}}\right)$.

$\eta =\frac{W_{output}}{W_{input}}$

Hence, from the formulas, for a machine of a given design due to friction and weight of the moving parts of a machine, the velocity ratio $\left(\mathrm{VR}\right)$ will not change, but mechanical advantage $\left(\mathrm{ME}\right)$ and efficiency $\left(\eta \right)$ will decrease.