Two rectangular pieces of plane glass are laid one upon the other on a table. a thin strip of paper is placed between them at one edge so that a very thin wedge of air is formed. the plates are illuminated at normal incidence by 545 nm light from a mercury-vapor lamp. interference fringes are formed, with 20.0 fringes per centimeter. find the angle of the wedge?

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?