A wooden block of mass slides across a horizontal tabletop with kinetic friction…
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A wooden block of mass m slides across a horizontal tabletop with kinetic friction coefficient μk. A light cord wrapped around a horizontal pulley is attached to the block and is pulled with a constant horizontal force F by a student standing next to the table. Treat the cord and pulley as ideal.
(1) Choose the system to be the block alone. List all forces acting on this system and classify each as internal or external. Justify your classifications.
(2) Choose the system to be block + Earth. Repeat the force classification and comment on whether the friction force is internal or external in this case.
(3) Choose the system to be block + cord + pulley (but not the Earth). Classify the forces acting on this system, paying special attention to the pulling force applied by the student. Explain how your classifications determine whether the net external force on each chosen system is equal to, greater than, or less than F.
(4) For each of the three system choices above, state whether that system will accelerate across the table and provide a brief explanation based on your force classifications.