Answer
The man has to apply a total force of $594.3N$
Work Step by Step
The man hanging upside down has to provide 2 forces:
- An upward force $F$ that supports and balances his partner's weight. In other words, $F=W_{partner}=475N$
- Centripetal force $F_c$ for his partner's circular motion
To find $F_c$, we already know $r=6.5m$ and $v=4m/s$. The partner's mass $m=\frac{W}{9.8}=48.47kg$
Therefore, $$F_c=\frac{mv^2}{r}=119.3N$$
So, $$\sum F=F+F_c=594.3N$$
