PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Three blocks—P, Q, and R—each rest on separate horizontal surfaces. For each block, a student has measured and listed all the horizontal forces acting on that block at a particular instant. Positive values indicate forces toward the +x direction, and negative values indicate forces toward the −x direction.
(a) For block P, the recorded forces are +3N, +2N, and −5N. Calculate the net horizontal force on block P and state whether it is in translational equilibrium.
(b) For block Q, the recorded forces are +4N, −1N, and −3N. Calculate the net horizontal force on block Q and state whether it is in translational equilibrium.
(c) For block R, the recorded forces are +6N, −2N, and −4N. Calculate the net horizontal force on block R and state whether it is in translational equilibrium.
(d) Summarize the criteria you used to decide equilibrium vs. nonequilibrium for the three blocks, and briefly explain why any two blocks with identical net forces must undergo the same qualitative change in velocity (if any).