Answer:
1. The frequency of the incident light must be equal to or greater than the threshold frequency of the photons before emission could take place.
2. The intensity of the incident light is proportional to the amount of photons released. The higher the intensity of light, the greater the amount of photons ejected.
Explanation:
1. Photoelectric effect is the process by which light with sufficient frequency falls on the surface of a material, e.g metal, to emit electrons. The incident light must have a minimum value of required frequency for the electrons to be ejected. This energy is termed work function which is a function of frequency.
So for emission to take place, the frequency of the incident light must be equal to or greater than the threshold frequency of the photons.
2. The intensity of light is a measure of the amount of light per unit area. When the intensity of incident light increases, the probability that photons would be released increases. The intensity of the incident light is proportional to the amount of photons released.
Assuming that the stone is thrown vertically... let's say it's a 1 kg stone.It doesn't matter if it's thrown upwards or downwards as (assuming no air friction) it will pass the original throwing point with the same downwards velocity as it had upwards, 3 seconds previously. So it starts with 1/2 m v^2 = 0.5 * 1 * 15^2 = 112.5 J of keThen k.e. gained = gpe lostk.e. gained = m g h = 1 * 10 * 50 = 500 J of Ke gainedso the final (total) ke is 612.5 J which = 1/2 m v^2 = 0.5 v^2 here
so 0.5 v^2 = 612.5so v^2 = 1225so v = 35 m/s
No, only average speed can be calculated from the distance of 90 meters and the time 3 seconds hope this helps
