Question

the reaction(s) of the pin support shown in the figure due to force f is (are) equivalent to:

reaction force

• a force of unknown direction and magnitude
• a force of unknown magnitude
• a moment of unknown magnitude
• a moment of unknown magnitude and direction

Explanation:

In engineering (a subfield of Natural Science), a pin support reaction has two components ($R_1$, $R_2$) which combine to a single force with unknown direction (since the angle of the resultant force is unknown) and unknown magnitude (until equilibrium equations are solved). Moments are not part of pin support reactions (they resist translation, not rotation; fixed supports resist moments). So the pin support reaction due to force F is a force of unknown direction and magnitude.

Answer:

a force of unknown direction and magnitude