A thin, rigid rod of negligible mass and length lies on a horizontal, frictionless…
PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A thin, rigid rod of negligible mass and length 1.5m lies on a horizontal, frictionless ice rink. Two identical 2.0kg blocks are firmly attached to the rod, one at each end. Initially the system is at rest. A small explosive charge at the center of the rod simultaneously ejects the two blocks so that they each move radially outward along the rod with speed 3.0ms−1 relative to the rod. Assume the explosion is symmetric and lasts a negligible time.
Ignore air resistance and any interaction with the ice other than the normal force.
(a) Identify a convenient axis about which to analyze the motion so that angular momentum is conserved during the explosion. Justify your choice with reference to external torques.
(b) Derive an expression for the angular speed ω of the rod–block system just after the explosion, in terms of the given quantities.
(c) Compute the numerical value of ω for the data provided.
(d) Discuss qualitatively how your answer to part (c) would change if the ice surface exerted a small but constant kinetic friction force on each block during their outward motion along the rod.