Ball b, with a mass of 30kg, is moving to the left at 10 m/s. with what velocity should ball a, with a mass of 10kg, move to the right and collide with 2, so that ball a rebounds with a velocity of 30 m/s, and ball b with velocity of 10 m/s? assume the collison to be perfectly elastic.

Light from two different sources are incident upon the same side of a polarizing filter. light from one source is polarized with total intensity ip, while light from the other source is unpolarized with total intensity iu. as you rotate the polarizing filter through 360 degrees, the intensity of the transmitted light on the other side varies by a factor of 9. what is the relative intensity of the initial polarized source to the unpolarized source, or ip/iu?