When is momentum conserved?
a. it is always conserved.

b. momentum is conserved when the system is closed, which means there are no forces, like friction, acting on it.

c. it is conserved when only two objects collide; more than two objects can't conserve momentum.

d. momentum is never conserved.

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