Force Equilibrium on Inclined Plane · PhysicsBowl 2015 #24
Physics · mechanics
Problem
A mass on a frictionless incline has a gravitational force, a normal force from the incline, and a force applied by a person that all are equal in magnitude. The mass remains at rest and the incline makes an angle θ counterclockwise from the horizontal. Which one of the following choices best describes the orientation of the applied force by the person? The +x-axis is directed upward, parallel to the incline's surface as shown in the figure.
[Figure: Inclined plane at angle θ with +x axis marked parallel to incline surface]
(A) The applied force is oriented directly along the +x axis.
(B) The applied force is oriented at an angle θ clockwise from the +x axis.
(C) The applied force is oriented at an angle 90°−θ clockwise from the +x axis.
(D) The applied force is oriented at an angle 90°−θ counterclockwise from the +x axis.
(E) This is a completely impossible situation that never can be realized physically.