Watersheds provide many of us with our drinking water supply, plus recreational opportunities and aesthetic beauty. Watersheds are areas from which water runs into a public water supply. Thus, much of the water you drink from a public source has passed through a watershed. Because of this, it's important that care be taken to minimize any contaminents that may find their way into a public water supply. A small example of a watershed would be the hills around a reservoir. A larger example would be the portions of Pennsylvania, New York, Virginia, Maryland, Delaware and Washington DC that are designated Chesapeake Bay watershed.
The light does not undergo a phase change.
Also, the surface of a mirror is a rigid boundary.
-- If it's all happening horizontally, then gravity is not involved.
Only the spring is.
-- If there's no friction, then total energy is conserved.
-- If you put 190J of energy into the spring by moving the mass,
and there's only 55J of potential energy in the spring now, then
the other 135J of energy is in the kinetic energy of the mass and
the moving parts of the spring.
Answer
given,


mass of book = 0.305 Kg
so, from the diagram attached below




computing horizontal component




θ = 62.35°