Final Answer:
The magnitude of the normal force exerted on the rod by the surface is option B: 14 N.
Step-by-step explanation:
The normal force exerted on an object on a flat surface is equal in magnitude and opposite in direction to the object's weight. In this case, the weight of the rod is given as 14 N. According to Newton's third law, the normal force exerted by the surface on the rod, in equilibrium, would be equal to the weight of the rod, which is 14 N. Therefore, the correct answer is option B, 14 N.
In more detail, when an object rests on a surface without any vertical acceleration, the forces acting on it must balance out. In this scenario, the weight of the rod is the force acting downward, and the normal force exerted by the surface counters this weight, acting upward. Mathematically, F_normal = Weight of the rod = 14 N, according to the given information. This equality ensures the rod remains in equilibrium, neither sinking into nor floating above the surface.
Understanding Newton's third law helps solve such problems; it states that for every action, there is an equal and opposite reaction. Hence, the normal force experienced by the rod due to the surface is precisely the same in magnitude as the rod's weight but acts in the opposite direction, ensuring equilibrium in this setup. Therefore, the normal force exerted on the rod by the surface is 14 N, aligning with the selected option B.
Here is complete question;
"The uniform rod in figure 8.17 has a weight of 14 N. What is the magnitude of the normal force exerted on the rod by the surface?
A. 7 N
B. 14 N
C. 20 N
D. 28 N
E. None of the above / Cannot be determined with the given information."