## College Physics (7th Edition)

(a) $W=mg$ $N=mg\cos\theta$ As the plane is inclined, $\theta$ can't be 0. Therefore, $\cos\theta$ will always be less than 1. In other words, $mg\cos\theta\lt mg$ Or $N\lt W$. The normal force is (1) less than the weight of the object if it is placed in an inclined plane. (b) $Weight=mg=10\,kg\times9.8\,m/s^{2}=98\,N$ Normal force $N=mg\cos\theta =10\,kg\times9.8\,m/s^{2}\times\cos 30^{\circ}=85\,N$