Answer:
Width of the slit will be equal to 1.47 mm
Explanation:
We have given wavelength of the light 
Distance D = 8 m
Distance between first minimum dark fringe and the central maximum is 2 mm
So 
We have to find the width of the slit
For the first order wavelength is equal to 
, here a width of slit
So 
So width of the slit will be equal to 1.47 mm
A single polarizer will stop 50% of the incoming light.
Because the gravitational force, which points downward, is perfectly balanced by the normal reaction of the floor of the bowling lane, which points upward. The two forces are equal in magnitude, so the net force acting vertically on the bowling ball is zero, therefore there is no acceleration along this direction. Moreover, since the ball is moving in the horizontal direction, the gravitational force has no component along this direction, so it does not change the velocity of the ball.
