What Kepler's constant ? ? ! ?
The only constant in Kepler's laws is in the third one, where it says something to the
effect that (square of a body's period) / (cube of its distance from the central body)
is a constant.
That means it's a constant for multiple little ones orbiting the same central body.
But it's not the same constant for other central bodies.
It's one constant for the planets, asteroids, and comets orbiting the sun.
It's a different constant for the moon, TV satellites, weather satellites,
and military satellites orbiting the Earth.
Answer:
The starting velocity for ball 1 is 1.00 meter/second. Its ending velocity is 0.25 meter/second.
The change in velocity for ball 1 is 0.25 – 1.00 = -0.75 meter/seconds
The intensity of the light has no connection with the photoelectric effect.
That's what was so baffling about it before the particle nature of light
was suspected ... a match with a blue flame might stimulate the
photoelectric effect, but a high-power red searchlight couldn't do it.