Unpolarized light, with an intensity of i0, is incident on an ideal polarizer. a second ideal polarizer is immediately behind the first, and its axis of polarization is parallel to the first polarizer’s. how much of the light will be transmitted through the system?

Io/2

Explanation:

According to the law of Malus, the intensity of transmitted light after first polarizer is

where, Ф be the angle between the axis of polarizer and analyser.

As teh mean value of Cos^Ф is 1/2, so the intensity of light transmitted from the first polarizer is

I = Io/2

Nnow it passes through another polaizer which is parallel to the first polaizer is same as I. It means the intensity of transmitted light is Io / 2 .

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.