To understand the photoelectric effect physiciests should view light as having what type of properties?

Particle

Explanation:

To understand photoelectric effect the physicists has to view light as a particle and not wave. The wave nature of the light could not explain the phenomenon of photoelectric effect.

Photoelectric effect is emission of electrons from a material when electromagnetic radiation(Light) is incident on it. These emitted electrons are called photoelectrons.

The explain this effect Einstein proposed that beam of light is can not be a wave propagating through space, but a swarm of discrete energy packets, called as photons.

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.