A 5-kg mass is pulled up a smooth incline at a constant speed by a rope. The rope is parallel with the surface of the incline. If the incline is 50° relative to the horizontal, the normal force exerted by the incline on the mass is
A) 28 N.
B) 38 N.
C) 31 N.
D) 45 N.

Question

Quizplus · Accepted Answer

The normal force can be found by considering the components of the gravitational force perpendicular to the incline. The gravitational force acting on the mass is $mg$, where $m = 5\, \text{kg}$ and $g = 9.8\, \text{m/s}^2$. The component of this force perpendicular to the incline is $mg \cos(\theta)$, where $\theta = 50^\circ$. Thus, the normal force $N = mg \cos(50^\circ) = 5 \times 9.8 \times \cos(50^\circ) \approx 31\, \text{N}$.

A 5-Kg Mass Is Pulled Up a Smooth Incline at a Constant