# Question #18dea

The reactionary force $R$ exerted by the man on the floor of elevator is given by
$R = m \left(g + f\right)$
where m is the mass of the man f is the acceleration of the elevator $\left(f = 0 \text{ here}\right)$ and g is the acceleration due to gravity $g = 10 m {s}^{-} 2$.
So $R = m \left(g + f\right) = 84 k g \times 10 m {s}^{-} 2 = 840 N$