A rhinestone is made of flint glass with an index of refraction of 1.50. To make it more reflective, it is coated with a thin film of Si0 that has a refractive index of 2.00. Find the first two possible thicknesses of the SiO coating that provide strong reflection for 570 nm light at normal incidence.

Suppose that a cylindrical tank 6 meters high with a radius of 2 meters is filled to the rim with water. the tank is buried so that the top of the tank is 1 meter below ground level. the space above the tank is not filled with water. calculate how much work needs to be done by a pump to pump the water out of the tank up to ground level. (the water weighs 9,800 newtons per cubic meter.)