Answer:
Frequency
Explanation:
The property of waves that remains unchanged as it crosses the boundary of one medium to another is the frequency of the wave.
As a wave moves from one boundary to another, the wavelength and the speed of the wave changes.
The speed of the wave is product of wavelength and frequency. Also, the wavelength of the wave is function of the distance between successive crests or troughs of a wave.
The frequency of a wave is the number of waves that crosses a medium per unit of time.
Ultraviolet radiation from the sun is controlled by the ozone but if it infiltrates into the atmosphere it becomes a hazard. The uv reaches our eyes and darkens the retina and blurs vision. The fovea becomes insensitive and the cells dormant. This causes gradual blindness.
Answer:
The person on the truck would have the same speed as that of the truck. Also, before the ball is thrown, the ball would have the speed as that of the truck.
It is possible for a person standing at the side of the road to view the falling straight down. This would be possible if the ball is thrown backwards with the same magnitude of velocity as that of truck.
To the person on the truck, the ball would appear to have forward motion with the speed of the truck.
I’m pretty sure light. But I’m not 100% sure
