Two birds collide in midair. Before the collision, their combined momentum was 15 kg•m/s to the north. What is their combined momentum after the
collision?
A. 15 kg•m/s south
OB. 15 kg•m/s down
O c. 15 kg•m/s north
D. 15 kg•m/s east

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