A1 kg object is moving horizontally at 10 m/s when it hits and bounces off of the lower end of a bar hanging vertically at rest. assume kinetic energy is conserved. the bar has a length l of 1.2 m and a mass m of 3 kg and is pivoted about the upper end. immediately after the collision, the object moves with speed v at an angle  relative to its original direction. the bar swings freely and reaches a maximum angle of 90° with respect to the vertical. the moment of inertia of the bar about the pivot is ibar = ml²/3.