Physics · Mechanics

Five physical systems involve two objects labeled X and Y, and a reference point P. Match the descriptions in Column I with the physical setups in Column II. Column I (Statements): A. Force exerted by X on Y has magnitude Mg. B. Gravitational potential energy of Y (or part of system) is continuously increasing. C. Mechanical energy of system X+Y is continuously decreasing. D. Torque of the weight of Y about point P is zero. Column II (Systems): (p) Block Y of mass M slides on a fixed inclined plane X with constant velocity. P is a point on the plane. (q) Ring magnets Y and Z of mass M each repel each other. Y rests on base X, Z hangs in equilibrium. The whole system is inside a lift moving upward at constant velocity. P is the top of the stand. (r) Pulley Y of mass m0 is fixed to a table X. A block of mass M hangs from a string passing over the pulley. The system is in a lift moving downward at constant velocity. P is fixed on the table. (s) Sphere Y of mass M moves down in a non-viscous liquid X at rest in a container. P is a reference point. (t) Sphere Y of mass M falls with terminal velocity in a viscous liquid X. P is a reference point.