PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
A 2.0 kg puck moves on a horizontal air table. Starting from the origin, the puck is pushed at constant speed around the perimeter of a rectangle whose sides are 3.0 m (along the x-axis) and 4.0 m (along the y-axis) before returning to the origin. Three horizontal forces act on the puck throughout the motion:
• Force A: a constant 5.0 N force directed rightward ( +x direction ).
• Force B: a constant 2.0 N force directed leftward ( −x direction ).
• Force C: a kinetic friction force whose magnitude is 1.0 N and whose direction is always opposite the puck’s instantaneous motion.
Assume no other forces do work.
(a) Calculate the net work done on the puck by Force A for the entire closed rectangular path. Show all reasoning.
(b) Calculate the net work done on the puck by Force B for the entire closed rectangular path. Show all reasoning.
(c) Calculate the net work done on the puck by Force C for the entire closed rectangular path. Clearly indicate how you account for the direction of the puck’s motion on each side of the rectangle.
(d) Based on your results, classify each of the three forces as conservative or non-conservative. Justify each classification by explicitly referring to properties of the work you calculated.