A friend is running clockwise at a constant speed on a circular track. At the instant your friend is located due west of you, their velocity is in the direction pointing due east. What is the direction of your friend's angular momentum around you at that instant

1. do the particles in the medium material move in the same direction of the wave or at opposite direction to the wave? explain your answer. 2. by inputting more energy into the wave, i.e a large shake of the spring, which wave property also increases? 3. are there forces of friction acting while a wave is passing through a medium?