PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
On an inclined plane experiment, a student draws a free-body diagram for the block but places the normal-force arrow so that it begins on the plane’s surface and points perpendicular to the surface. The weight arrow begins at the block’s center, and no other forces are drawn. The block subsequently accelerates down the plane faster than predicted. Which statement best identifies the error in the diagram that could account for the inaccurate prediction?
(a) The normal-force arrow should originate at the block’s center of mass, not at the contact surface.
(b) A static-friction force opposite the impending motion was omitted from the diagram.
(c) The weight vector should have been resolved into components parallel and perpendicular to the plane on the diagram.
(d) The normal-force arrow should have been drawn vertically upward rather than perpendicular to the plane.