1. The problem statement, all variables and given/known data An object is in uniform circular horizontal motion at the end of a chord of length L. Its tangential speed is v. The chord is pulled in to length 0.5L in such a way that the tension in the chord remains constant. As a result, the tangential speed: a) remains constant b) increases to 2v c) decreases to 0.5v d) increases to 1.4v e) decreases to 0.7v 2. Relevant equations The correct answer is E. This can be solved using T = m * v^2/r approach. I get this, and I know how this works. 3. The attempt at a solution Here's what I though initially: we do not have any net torques on the system [using an analogy of planetary motion around the sun, where angular momentum is conserved, substituting Tension force for gravitational force], so angular momentum has to be conserved. Thus: Li = Lf [m*v*r]i = [m*v*r]f I eliminate the m's, and then plug: v*L = x * 0.5 L thus x = 2v, which is b, an incorrect answer. Could anyone please explain why this approach is incorrect? Thanks in advance for the assistance!