posted by Mischa .
A bird perched on a swing the sits 8 cm below a bar has a mass of 52 g, and the base of the swing has a mass of 153 g. The swing and bird are originally at rest, and then the bird takes of horizontally at 2 m/s. How high will the base of the swing rise above its original level (disregard friction)?
Use conservation of momentum:
then, having the velocit of swing, determine its KEnergy. That kE will equal gravitational PE, or mgh.