Question

A couple of $50Nm$acts on a rigid body when a pair of unlike parallel forces of magnitude each$125N$acts on it. Calculate the arm of the couple.

Answer 1

Step 1-Given data

Moment of the couple, M= $50Nm$

Couple force, $F_1=F_2=125\hspace{0.17em}N$

Arm of the couple. d=?

Step 2-Formula used

$$\begin{gathered} Momentofcouple=Anyoneforceofthecouple\times couplearm \\ M=F_1\times d \end{gathered}$$

Step 3-The arm of the couple is

Calculation;

$$\begin{gathered} M=F_1\times d \\ 50Nm=125N\times d \\ 50=125\times d \\ d=\frac{50}{125} \\ =0.4 \\ d=0.4m \\ or,d=40cm \end{gathered}$$

Hence, the length of a couple's arm is$40cm$.