Black holes is exists
Black holes is highly gravitional wave field in space
Compared with an Earth year, a galactic year represents time on a grand scale but its not a consistent measurement across the galaxy
Refraction is the change in direction of a wave, caused by the change in the wave's speed. Examples of waves include sound waves and light waves. Refraction is seen most often when a wave passes from one transparent medium to another transparent medium. Different types of medium include air and water. When a wave passes from one transparent medium to another transparent medium, the wave will change its speed and its direction. For example, when a light wave travels through air and then passes into water, the wave will slow and change direction.
Answer:
Explanation:
work done=force*displacement
=350N*15m
=5250 joule