Three hockey pucks slide without friction on a straight section of perfectly smooth ice
PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
Three hockey pucks slide without friction on a straight section of perfectly smooth ice. Puck P (0.20\,kg) moves east at 2.5\,m/s. Puck Q (0.30\,kg) moves west at 1.5\,m/s along the same line. At t=0 the center of puck P is at x=0 and the center of puck Q is at x=0.60m. A stationary puck R (0.40\,kg) is at x=1.10m. All pucks have negligible thickness so they collide when their centers coincide. The collision between pucks P and Q is perfectly elastic, while the collision between Q (or any combination containing Q) and puck R is perfectly inelastic. Neglect any other interactions.
(a) Determine which two pucks collide first. Show all reasoning clearly.
(b) Calculate the velocities (magnitude and direction) of the colliding pucks immediately after their first collision.
(c) Determine the time elapsed between the first and second collisions.
(d) After all collisions have ceased, state the final velocity of each puck and calculate the percentage of the total kinetic energy lost in the entire sequence.