<p>I'm doing a review packet right now, and I'm stumped on this one problem:</p>
<p>A swing seat of mass M is connected to a fixed point P by a massless cord of length L. A child aso of mass M sits on the seat and begins to swing with zero velocity at a position at which the cord makes a 60 degree angle with the vertical. The swing continues down until the cord is exactly vertical at which time the child jumps off in a horizontal direction. The swing continues in the same direction until the cord makes a 45 degree angle with the vertical as shown in figure II; at that point it begins to swing in the reverse direction. With what velocity relative to the ground did the child leave the swing?</p>
<p>At first just do some trig to find how high above the 0 point (the point where the swing is perfectly vertical) the swing is at its initial position. Use conservation of energy to see how fast it is going at the bottom, then do trig for the final position to see how far above the zero point it is, then see how much energy it has there. You know the differences in energy will result in different velocities at the bottom, which you find with conservation of momentum that slak posted.</p>