## Essential University Physics: Volume 1 (4th Edition)

$\theta = cos ^{-1} (580/700)=34^{\circ}$
They can cross the bridge safely. We know that the force, 700 N, times the cosine of the incline angle of the bridge gives the normal force. Thus, we see: $F_{max}= Ncos( \theta)$ $\theta = cos ^{-1} (F_{max}/N)$ This gives: $\theta = cos ^{-1} (580/700)=34^{\circ}$