A0.320 kg puck at rest on a horizontal frictionless surface is struck by a 0.220 kg puck moving in the positive x direction with a speed of 4.09 m/s. after the collision, the 0.220 kg puck has a speed of 1.29 m/s at an angle of θ = 60.0° counterclockwise from the positive x axis. (a) determine the velocity of the 0.320 kg puck after the collision. express your answer in vector form. vf = m/s (b) find the percent of kinetic energy lost in the collision.

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)