An incident light ray hits a plane surface at 20 degrees (hint: remember where the angle is measured from). What is the angle between the incident and reflected rays? So is it 20 degrees or 40 degrees

A1-lb collar is attached to a spring and slides without friction along a circular rod in a vertical plane. the spring has an undeformed length of 5 in. and a constant k =25 lb/ft. knowing that the collar is released from being held at a determine, the speed of the collar and the normal force between the collar and the rod as the collar passes through b.