A ball is thrown vertically upwards from the roof of a building with an initial velocity of 30 m / s. If it stops in the air 220 m above the ground, what is the height of the building?

Will you chech and finish these for me, because i am stumped with them.

Smallest intensity of a stimulus that you can detect 50 percent of the time is

Ascientist notices that an oil slick floating on water when viewed from above has many different colors reflecting off the surface, making it look rainbow-like (an effect known as iridescence). she aims a spectrometer at a particular spot and measures the wavelength to be 750 nm (in air). the index of refraction of water is 1.3