7. When initially-unpolarized light passes through three polarizing filters, each oriented at 45 degree angles from the preceding filter, of the initial light passes through the last filter.

Explanation:

Let the intensity  of unpolarised light be I₀ . After passing through the first polarising filter , the intensity  is I₀ / 2 .

After second filter , the intensity  will be  I₀ / 2 x cos²45 =  I₀ / 4

After third filter , the intensity will be I₀ / 4  x cos²45 = I₀ / 8 .

So,

1 / 8 the of initial light passes through the last filter .

when the velocity of a mass on a spring is zero, the acceleration is at a maximum .

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.